Dawson Dean - Tips And Tricks

Linux

Installing and configuring Linux
Setting up Linux Disks and a Samba File Server on Fedora
Installing and configuring Emacs
Emacs Common Things
vi editor
GDB (GNU Debugger)
Burning DVDs on Linux
gprof (GNU Profiler)
Compiling Linux programs with static libraries
Installing and configuring Apache

Raspberry Pi

Installing Raspberry Pi

Debugging Tips

Pytorch Problems and Solutions

Common Programs

Git
Microsoft Excel

Web

Using CSS "position" attributes for HTML Layout

Git and GitHub

Overview

A repository, often called a repo, is a directory of files. Every directry under source conntrol is a complete independant repository, and can function even without network access.

The basic structures are:

Workspace - a directory of files
Staging Environment (also called the Index) - a data file used by Git to track files. The "index" holds a snapshot of the changes to the working tree that will be used for the next commit. If you just edit a file but don't add it to the index, then those changes will not be saved. Instead, you first use the "git add" command to add the changes to a commit record, and then the "git commit" command to integrate that commit with a repository.
You can have several active Staging Environments in a single repository. This means you can work on different unrelated changes, and comit them independantly, all in a single directory.
HEAD - the last commit
Local Repo - Locally committed files. This is actually a .git file in each directory. The local Repo is a file, not a separate directory.
GitHub Repo - Remotely committed files

When sharing work with other users, there is no special "central" repository. All repositories are equal in the eyes of git. Instead of checking an updated file into a source control central server, with Git you push or pull commits from one repository to another. In practice, one repository may be treated specially, like a central master, but that is outside of git. Different organizations may use different policies for identifying or protecting different special repositories.

GitHub is a web-based server where people can exchange and share a source tree. You can push your local repository to the server, and can pull repositories from the server to your local repository. It also lets people chat and read each other's source code. You do not need GitHub to use Git, but you do use git to interact with GitHub. Git does everything on the local computer, and GitHub is a web service that allows sharing between different git users. Git can also work with other similar services.

Login to GitHub at https://github.com and create a Free account.
WARNING! Use the same email you used for the local repository!

The git cheat sheet (in English) https://training.github.com/downloads/github-git-cheat-sheet.pdf

Some handy tutorials

https://git-scm.com/book/en/v2/Getting-Started-First-Time-Git-Setup
https://product.hubspot.com/blog/git-and-github-tutorial-for-beginners
https://git-scm.com/book/en/v2/Git-Basics-Recording-Changes-to-the-Repository
https://www.atlassian.com/git/tutorials/setting-up-a-repository
https://kbroman.org/github_tutorial/pages/init.html
https://git-scm.com/docs
https://rogerdudler.github.io/git-guide/
https://www.coursera.org/learn/data-scientists-tools/lecture/qmyW6/introduction-to-git
https://stackoverflow.com/questions/21692155/whats-the-difference-between-working-directory-and-local-repository

Installation

Install and configure the software On Fedora: sudo dnf install git-all
On non-Linux systems, download Git - http://git-scm.com/downloads
Create a user. You only need to do this once. git config --global user.name "John Doe" git config --global user.email myEmail git config --global core.editor emacs
To view users git config --list

Creating repositories

Each directory of source code requires a separate repository.

Create a repository on a local machine:
This will create a subdirectory named ".git" to the directory.
- Make a directory and cd to the directory
- run "git init" to initialize the repository for this local directory.
- Optionally run: git config format.pretty oneline
Make a local copy of a repository on GitHub
This will make a "clone" of a GitHub repository.
- Make a directory and cd to the directory
- run "git init" to initialize the repository for this local directory.
- git clone https://github.com/dfdean/MedNoteMaker
- git clone https://github.com/dfdean/mlLib
  for examle git clone https://github.com/dfdean/MedNoteMaker
Add a git repository to an existing directory of other files that are not in the repository.
- Make a temporary directory and cd to it
- run "git init" to initialize the repository for this temp directory.
- git clone https://github.com/dfdean/MedNoteMaker
  for examle git clone https://github.com/dfdean/MedNoteMaker
  Now, cp -r the .git directory to your final target directory
  Delete the tempory directory - it is no longer needed
  cd to the target directory
  git reset --hard HEAD
  git pull

Modifying and Committing Files

The states of a file are: Tracked ---> Modified ---> Staged ---> Committed/Tracked
A key idea in git is that changes are not stored as diffs, but rather as stand-alone snapshots.

TRACKED state - Add existing files to a repository
This adds a previously untracked file to the index and places it in the "Tracked" state. This command tells git to manage the file; it does NOT commit the file. You only do this once for a file, and after that it is in a TRACKED or MODIFIED or COMMITTED state. git add fileName
MODIFIED state
Git seems to use local file timestamps to decide which files have been modified. Any time you change a file, such as in a text editor, Git will mark it as modified.
STAGED state - Staging a tracked file
Staging adds the current snapshot of a file to the list of changes for the next commit. git add myFileName
Note, that this uses git "add", even though the file was previously tracked. Here "add" means to add a file to the next commit list, not add a file to the repository. So, you will "add" the same file every time you edit and commit it.
Note also that when you add a file, git takes a snapshot of that file to use for the next commit. If you change a file after calling "git add" then you must add again to save the new changes. A single file may be in both the unstaged and staged state, which means one snapshot of the file was staged, and then the file is modified again after staging, so the new later changes to the same file has not yet been staged.
COMMITTED state - commit local changes to a repo
A key idea in git is that changes are not stored as diffs, but rather as stand-alone snapshots. A commit is an object stored in the repository; and the commit contains metadata and pointers to the blob objects for a snapshot of each file. Each snapshot referenced by the commit is a complete file, *including* all new changes.
To create a "commit" object referencing all files in the MODIFIED state git commit This will launch an editor where you can enter the commit message. When you edit the editor subprocess back into git, git will then save all changes. Or, you can skip the editor with the following: git commit -m "message"
Alternatively, you can commit *ALL* modified and tracked files. This will stage every modified file and then commit them all. git commit -a
Remember, there are TWO "add" commands. One to add the file to TRACKED and a second to move it to STAGED. git add myFileName git add myFileName git commit -m "commit message"

If you are only working on a local storage (no GitHub or BitBucket or other remote store) then you are done. Your changes are saved. If you delete the working copy of the file, then do a "git reset --hard HEAD" the file will be restored.

If you want to use GitHub, then you ALSO need to do the next steps.

Next make a branch. In git, a branch is a reference to a commit. This becomes important when you have several commits in a directory, each with different set of snapshots of files. You use branch names to reference each commit. In practice, this means you specify a branch name to the command that changes the current working environment to reference a particlar commit.

git checkout -b myBranchName
Here myBranchName is any string used as the name of the branch

Now, push a branch to Github git push origin my-new-branch Here, "origin" is just a special keyword that means the remote URL associated with this repository Or, you can try this, but I have to enter SSH public key passcodes which takes extra configuration. git push git@github.com:git/git.git yourbranchname

Now you can log into GitHub and create a pull request, examine the diff, and merge it into the main branch.

Getting Updates

In a directory that is a clone of a repository on GitHub git pull origin master

To dischard all local changes and replace the directory with the remote repository git reset --hard HEAD git pull

To restore the state of a file from your local repository git checkout However, if you deleted a file, then you will have to name it to restore it from the local repository. git checkout myFileName

`Status Commands`

To see what has changed but not been committed in the working directory git status

To see which branch you are currently working on git branch

To see what remote repository git remote -v

To see what has been changed and committed in the past: git log

To see what changes are changed but not yet staged. Shows the differences between the working directory and the index. Note, if all changes are staged but not yet committed then "git diff" will show nothing. git diff git diff [fileName] git diff [tag name]

The changes are in the current staged commit. These files have been added to the index and staged for a commit. These are the changes between the index and the HEAD (which is the last commit on this branch). git diff --staged

Shows the changes between the index and the HEAD (which is the last commit on this branch). git diff --cached

Shows all the changes between the working directory and HEAD (which includes changes in the index). This shows all the changes since the last commit, whether or not they have been staged for commit or not. git diff HEAD

`Delete/Undo Changes`

 To discard unsaved changes to a file. This updates the file witht he snapshot fromt he local saved head. This does not pull files from Github - instead it only does a local restore. 
git checkout -- fileName 
git checkout -- '*.c'  
To Delete a file from the index There are several ways to do this: 
 Delete a TRACKED or MODIFIED file from the repo and also delete from the working directory. This will require a commit. 
git rm fileName 
git commit  
Delete a file that is STAGED (it has been added but not yet committed). 
git rm -f fileName  
Remove a file from the index but leave the file in the directory. This is useful if you accidentally add a file, like a binary, that you no longer want tracked. 
git rm --cached fileName 
  
Rename or move a file in the index 
git mv oldName newName



 
   GDB
 
 GDB in Emacs
 A good tutorial is http://tedlab.mit.edu/~dr/gdbintro.html  Control-x 2 - Split the screen 
Esc-X gdb - Start gdb 
Esc-X gud-gdb - Start GUD gdb 
{program name} - type this at the "Run gdb" prompt in the mini-buffer 
Optionally, type "set args xxxx" to the prompt, which will set the command line arguments to xxxx. 
 
 
 GDB Commands
 See the manual for more information.  file - Load a new program 
r - Run the current program 
k - Kill the current debugged process 
 Execution  s - Step Into 
n - Step Over 
c - Continue 
jump lineNum - Jump to lineNum in the current file 
fin - Run until the current function finishes 
 Stack  bt - Print the call stack 
f n - Set the current stack frame to frame #n 
p {var name} - Print the value of the named variable 
 Breakpoints  b {proc name or lineNum} - Set a breakpoint at the entry to the named procedure. If this is a lineNum then it assumes the current file being debugged. 
d {num} - Delete breakpoint number 
info break - List breakpoints 
 

 
   gprof (GNU Profiler)
 
 Using gprof
  Compile with -pg flag 
run the program as you normally would. This creates a gmon.out file 
gprof {programName} gmon.out > prof.txt 
 

 
  Microsoft Excel
 
 Making a Cell whose value is defined by an expression Select the cell, and type the expression in the fx (function) text box. Start the string with "=" to tell Excel that this is a formula and not a string value. 
Example: 
 =(L2 / (K2 + L2)) * 100  
The parameters refer to cells. These take the form of  where  is a letter and  is a number. A "$" symbol in front of either the column or letter means it is absolute address, which is independent of the location of the cell making the reference. No "$" means that this address is relative to the cell making the reference. This can have several combinations:

Type	Description	Example
Absolute	A specific cell independent of location of the referencing cell	$A$1
Absolute Column, Relative Row	A cell in a specific column, and in a row relative to the referencing cell	$A1
Absolute Row, Relative Column	A cell in a specific row, and in a column relative to the referencing cell	A$1
Relative	A cell in a relative row and column to the referencing cell	A1

 
Once you have a cell with a formula, you can select it and drag the outline to fill a column or row. This will put that expression in every cell in the region. Assuming that hte formula uses relative cell references, this means every cell will have a value dependent on relative cells in its own row or column. 
NOTE: The first cell uses relative addresses with specific constant names, like "A3" and so on. When you copy this to other cells, Excel will first convert the specific names (like "A3") to relative positions (like, one column to the left and two rows up) and then put the appropriate relative positions in each new cell. So, you define the pattern with a specific example and then Excel generalizes this and makes new specific constants for each new cell. 
Besides algebraic expressions, there are a few built-in functions that are handy. 
 SUM(A1:A3) 
AVERAGE(A1:A3) 
MAX(A1:A3) 
MIN(A1:A3) 
 
 Creating a series of auto-fill data in rows or columns  Click a cell, which should show a dark frame around the cell, with a box in the lower right corner. Select the box, and drag it to expand the region to a row or column or block of cells. 
Select the "Home" tab, then click the "Fill" combo box, then select the "Series..." item. This lets you control how data is filled in the selected region. 
 
 Counting the Number of rows that Meet a Condition  =CountIf(range, criteria) 
 where 
 Range is a range of cells, like "A2:A7" 
Criteria is a quoted algebraic relation, like ">=2001" 
 Some examples 
 =CountIf(A2:A7, ">=2001") 
 Some extensions 
 Combine several COUNTIF expressions in a SUM expression 
 

 
  A few personal things for installing and configuring Linux
 This is just my personal To-Do list for installine a new Fedora machine. This will probably not be useful to anyone else. This is also Fedora-specific, which uses yum. Debian and Ubuntu systems will use an alternate system, apt-get. Yum 
yum is a wrapper for the RedHat package manager (rpm) which works on Fedora or Red Hat systems. It runs as root. Here are the common yum commands: 
  yum update 
 yum list <package name> 
 yum list updates 
 yum list recent 
 yum list installed 
 yum search <name> - looks for a string in package names and descriptions 
 yum info <package name> 
 yum install <package name> 
 yum remove <package name> 
 

 


  After installing from the DVD, I add additional accounts (fsuser, root2, etc).  
Use the Software Package tool to get the latest system updates  
Use the Software Package tool to install "Gnome Tweak"  
Go through Tweak and Settings tools  
Use the Software Package tool to install Emacs  
Copy working directories and files  Copy ddRoot and dLargeData directories from a recent backup  
Copy .emacs and .bashrc from ddRoot/tools to the home directory 
Run ibus-setup, then in the "emoji" section, disable the keyboard shortcut Ctrl-period 
  
Bash tweaks  sudo dnf install bash-completion 
  
Configure Firefox  Configure Firefox (homePage, font size, show Home button, newTab page)  
Install PrivacyBadger: https://privacybadger.org/ which blocks tracking scripts  
Install uBlock Origin: https://addons.mozilla.org/en-US/firefox/addon/ublock-origin/ 
  
Install and Configure Chrome  Install Chrome from https://www.google.com/chrome/browser/desktop/index.html  
Configure Chrome (homePage, font size, show Home button, newTab page)  
Install PrivacyBadger: https://privacybadger.org/ which blocks tracking scripts  
Install uBlock Origin: https://github.com/gorhill/uBlock#ublock-origin 
  
Install gcc and friends 
yum install gcc 
yum install gcc-c++ 
yum install glibc-static 
yum install libstdc++-static  
Install Extra Fedora Packages These contain extra packages that are not in default Fedora’s repositories, including proprietary and partially open source libs in the non-free. These are used by VLC and NVIDIA. 
 dnf install https://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm  
dnf install https://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-$(rpm -E %fedora).noarch.rpm 
 
Install VLC 
See https://www.videolan.org/vlc/download-fedora.html This requires Fedora 22 and later. 
This uses rpmfusion, and installs from rpmfusion-free-release-stable.noarch.rpm  Install rpmfusion packages as described above  
dnf install vlc  
dnf install python-vlc  
Download the appropriate libdvdcss package from https://www.rpmfind.net/linux/rpm2html/search.php?query=libdvdcss  
cd to the Downloads directory  
dnf install ./the-downloaded-libdvdcss package 
  
Installing PrivateInternetAccess VPN I use privateinternetaccess, so this is specific to their software. Different VPN's will have different installation steps. Moreover, PrivateInternetAccess has changed their installer, from dnf-based to an app you download from their web site. 
 Open a browser and go to https://www.privateinternetaccess.com/download/linux-vpn 
Download the app. This creates a file pia-linux-xxxxx-xxxxx.run 
chmod ugo+rwx ./pia-linux-xxxxx-xxxxx.run 
pia-linux-xxxxx-xxxxx.run 
Launch the PIA application 
Select options, and check to turn on PIA on system startup 
  
Install Password Manager Once I started using a password manager I wondered how I lived without one. But, I prefer to keep a local file that is password protected rather than a cloud-based service. A local file has a big inconvenience that I can't use it from a laptop while working or travelling. But, really, I don't want to be accessing financial or similar web sites from a coffee shop wifi. Keeping a local file means you first have to break into my house and then break into my computer and then break the file encryption to get my passwords. Sure, that's possible, but it adds another level of security which I prefer. I just fear that web-based password managers are too tempting a target and may some day be broken, particularly by a state agency. 
There are lot of password managers, and I used to use PasswordSafe because of its association with Bruce Schneier. However, that is not supported in the latest Fedora, so I changed to KeePass and am happy with it as well. 
I installed KeePass XC" through Fedora Software manager. There is also https://keepass.info/ 
 
Install NVIDIA drivers and CUDA I use the rpmfusion method. rpmfusion is already required for VLan and I also do not want to customize my NVIDIA driver install - I just want something that works. 
 Install rpmfusion packages as described above  
Disable secure boot, by booting with F2 and turning off the option  
sudo -i  
Find out what card you have installed: 
/sbin/lspci | grep -e VGA 
For example, I have an RTX A2000 Mobile (rev a1)  
dnf update -y  
dnf install akmod-nvidia  
dnf install xorg-x11-drv-nvidia-cuda  
Reboot  
To test the install: 
modinfo -F version nvidia 
nvidia-smi 
  
Install numpy and pytorch 
This assumes you have installed NVIDIA drivers and CUDA.  sudo -i 
python3 -m pip install numpy 
python3 -m pip install tables 
python3 -m pip install opencv-python 
python3 -m pip install matplotlib 
python3 -m pip install sklearn 
python3 -m pip install pylint 
python3 -m pip install flake8 
python3 -m pip install xgboost 
python3 -m pip install python-gnupg 
python3 -m pip install psutil 
python3 -m pip install boto3 
dnf install python3-tkinter 

 
Find out which version of CUDA is running: nvidia-smi  
To install Pytorch itself, go to the https://pytorch.org/get-started/locally/ 
Select the proper options in the table and it will give you an install line for Pytorch. 
Copy and paste this into the command line 
  
Installing Google Drive for Python on Fedora  Install and edit public keys. (see my private notes in the tools dir for that) 
Set up the Google Drive API for Python at https://developers.google.com/drive/api/v3/quickstart/python 
sudo -i 
python3 -m pip install google-api-python-client 
python3 -m pip install oauth2client 
  
Fixing Sound Issues 
I have not been able to make this work. I have NVIDIA drivers, which is the audio output. I ended up just using a USB audio card, but there seems to be a way to make this work.  Getting the audio module in use: 
lspci -v | grep -iA10 audio | grep modules (below, I assume this returns snd-hda-intel) 
cat /proc/asound/card*/codec* | grep Codec (below, I assume this returns Codec: Nvidia GPU a0 HDMI/DP) 
sudo -i 
echo "options snd-hda-intel model=auto" > /etc/modprobe.d/alsa.conf 
 
  
Misc  sudo -i 
yum install ftp 
yum install dvd+rw-tools 
dnf install -y gvfs-mtp 
yum install htop 
  
Software Tools  sudo -i 
npm install terser -g 
npm install html-minifier-terser -g 
  
Telegram  Download installer from https://telegram.org/dl/desktop/linux 
cd Downloads dir 
tar -xf ./tsetup.4.4.1.tar.xz (or use whatever file name is downloaded) 
mv Telegram ../tools/ 
  
Discord  Download installer from https://discord.com/ 
cd Downloads dir 
tar -xf ./Discord.tar.gz (or use whatever file name is downloaded) 
  
Thunderbird Email  sudo -i 
dnf install thunderbird -y 
  
Evolution Email  Install Evolution from Software Manager tool 
Go through View menu options (Preview=Vertical, Uncheck group by threads) 
Go through menu Edit>Preferences 
Setup gmail  Select the menu "Edit>Accounts" and then expand the list item for your email account, then expand the list item for "Mail Accounts" and then select the list item for your email account and click the "Edit" button. 
In the edit dialog, select "Receiving Email" and change the imap.googlemail.com to imap.gmail.com 
In the edit dialog, select "Sending Email" and change the smtp.googlemail.com to smtp.gmail.com 
 
Create an account for Local Archived files  Select the menu item File>New>Mail Account 
For the General Dialog, FillName=Local Archive emailAddress=emailArchive@dawsondean.com 
For the Receiving Email Dialog, accountType="Standard Unix mbox spool directory" spoolDirectory=[local archive dir] 
For the Receiving Options Dialog, deselect all options, these messages have already been filtered and saved. 
For the Sending Email Dialog, serverType=None 
For the Account Summary Dialog, name="Local Archive" 
 
  
Installing Git and Github gh command-line tool on Fedora  sudo -i 
dnf install git-all 
On non-Linux systems, download Git - http://git-scm.com/downloads 
dnf config-manager --add-repo https://cli.github.com/packages/rpm/gh-cli.repo 
dnf install gh 
 Create a user 
 git config --global user.name "xxxx xxxx" 
git config --global user.email xxxxx@gmail.com 
git config --global core.editor emacs 
git config --list 
 Install GitHub Desktop 
 Download the rpm from github https://github.com/shiftkey/desktop/releases 
sudo -i 
rpm -i GitHubDesktop-linux-2.9.6-linux1.rpm 
  
Installing Zoom on Fedora 
See https://support.zoom.us/hc/en-us/articles/204206269-Installing-Zoom-on-Linux  
Prusa Slicer 
The instructions are here  yum install gtk2 
Download the App.Image file 
chmod ugo+x xxxxxx.AppImage 
mkdir ~/tools 
cp ~/Downloads/PrusaSlicer-xxxxxxxx.AppImage ~/tools 
run ./tools/xxxxxx.AppImage 
 If you also need to upgrade the firmware, then follow these extra steps. See https://help.prusa3d.com/article/firmware-updating-mk3s-mk3s-mk3_2227 for details.  Download the .hex file 
sudo 
chmod ugo+rx /dev/ttyACM0 
Connect the USB cable from the computer to the printer 
./tools/xxxxxx.AppImage 
Select the meni "Configuration/Flash Printer Firmware" 
  
Microsoft Teams 
Microsoft Download Page  cd ~/Downloads 
sudo -i 
dnf localinstall teams[tab key] 
  
Disable Bell in shell windows Edit the "/etc/inputrc" to add the line: 
    set bell-style none
    
 
 
Automate backups and other tasks with cron  sudo -i 
dnf install cronie cronie-anacron 
python3 -m pip install boto3 
If cron is not running, use this to configure it to run at boot: 
systemctl enable crond.service 
Add this line to /etc/crontab 
0 2 * * * ddean /home/ddean/ddRoot/tools/offsiteBackup 
0 1 * * * ddean /home/ddean/ddRoot/tools/offsiteTasks 
Make sure the files offsiteBackup and offsiteTasks are executable 
chmod ugo+x offsiteBackup 
chmod ugo+x offsiteTasks 
  
Install user logon scripts  cp ~/ddRoot/tools/ddean.desktop ~/.config/autostart/ddean.desktop 
chmod ugo+x ~/.config/autostart/ddean.desktop 
  
Brother Printer Install the drivers    Open URL: http://support.brother.com/g/s/id/linux/en/faq_prn.html?c=us_ot&lang=en&redirect=on#f00104 
visit this URL: https://help.brother-usa.com/app/answers/detail/a_id/52188/p/9214/kw/Linux/session/L3RpbWUvMTU0ODEyOTc4Mi9zaWQvZlVJYjlFYTRNMURCVk11cW9zZVJsYlY4V2ozZl9HYzY5b2NHeE1MS1VMNzdjRV9HR1BsWFdwZkZVNFhqRjFEWmV3eUtLZWpnc3ZoRlpSYjd1WEpoVVVqZFlNZElYUDlIcURCd2lHelBlV3laSm1reWxFbFRucTF3JTIxJTIx 
 
sudo -i 
cd ~/Downloads 
./inux-brprinter-installerxxxxxxxxxxx 
Ctrl-D - exit su 
Open Control Panel 
Select the printer 
Click the gear icon 
Select "Printer Details" to open the configuration dialog box 
Click the "Select from Database..." button 
Scroll through the list to select the printer model number 
Close the dialog 
Click "Printer Options" 
Click "Test Page" 
 Install the scanner utilities  Look on the printer/scanner to determine its IP address. This assumes it is 192.168.1.xxxx 
vi /etc/sane.d/saned.conf 
Add 192.168.1.xxx to the config 
brsaneconfig4 -a name=Brother model=MFCL2750DW ip=192.168.1.xxxx 
gscan2pdf 
  
OBS (Open Broadcaster Software) Studio The installation instructions on the official project site are at https://obsproject.com/wiki/install-instructions#linux   Download some prereqs
 dnf install https://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm https://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-$(rpm -E %fedora).noarch.rpm 
 dnf install obs-studio 
 
  
Closure   Download the most recently released JAR file from the Maven repository https://mvnrepository.com/artifact/com.google.javascript/closure-compiler 
 Copy closure-compiler-xxxxxxx.jar to ~/tools 
 
  
Apache   sudo -i 
 dnf install httpd 
To have the server start at each boot: systemctl enable httpd.service 
To start the server now: systemctl start httpd.service 
 
 
 

 
 Connecting to Synology NAS A few common steps that I follow when managing disks on Synology NAS. Note - this is Fedora specific but may be close to what you would do on another distro. 
  
Mount the NAS on a Linux Client
   
Now look for IP addresses of other machines to see what is in use. This should confirm that the static IP we set up above is visible.  dnf install nmap 
nmap -sn 192.168.1.0/24 
nmap -sT -O 192.168.1.0/24 
  
Install the CIFS client software  sudo -i 
dnf install cifs-utils 
 
Make a place to mount the remove server  sudo -i 
 cd / 
 mkdir nas 
 chmod ugo+rwx nas 
  
Modify your /etc/fstab file. 
WARNING!!!!! Do NOT change any other line in the /etc/fstab file. This can make your system unusable and require a complete new OS install!!!! Only APPEND a new line. You have been warned. //192.168.1.10/fileroot /fileServer cifs guest,vers=3.0,noperm 0 0
 The option noperm in fstab tells the client to not do permission checks. This can expose files on this mount to access by other users on the local client system  
Reload the modified /etc/fstab file to remount all file systems  mount -a 
 
 
 192.168.1.2 

 
 Installing and configuring Linux Disks and Samba File Server A few common steps that I follow when managing disks and Samba on Fedora. Note - this is Fedora specific but may be close to what you would do on another distro. 
  
Format and mount a new disk
  GParted to determine the drive label  sudo -1 
dnf install gparted 
gparted 
 Run gparted to find the device for the new disk. All examples below assume /dev/sda but this will be different for each disk.  
Partition the disk 
This will make a numeric partition, like /dev/sda1 is the first partition of /dev/sda. Refer to that partition now.  fdisk /dev/sda 
n 
w 
 You can use lsblk to confirm the new partition is created.  
Make the file system. 
You can use "mkfs -v -t ext4 /dev/sda1" However, I just used gparted.  
Mount the FS  mkdir -v /fsDisk 
mount --source /dev/sda --target /fsDisk 
  
Some useful links:  Fedors docs 
 
  
 
Set a Static IP Address for your Server
 This uses a local IP address behind your router, so it is *only* visible on the local network.   
Get the local network device names  sudo -i 
dnf install lshw 
lshw -class network 
  
Or you can simply do this:  ifconfig 
 
So, why is this an odd name, like enp0s31f6 and now "eth0" or something? These are the new "Predictable network interface device names", which remain the same despite different physical and virtual network cards being added and removed. enp0s31f6 refers to ethernet (en), prefix 0 (p0), slot 31 (s31), function 6 (f6)  
See what the IP address of the local machine is  ip addr show 
  
Configure an interface with static network settings using ifcfg files For an interface with the name enp0s31f6, create a file with name ifcfg-enp0s31f6 in the /etc/sysconfig/network-scripts/ directory with content similar to this: DEVICE=enp0s31f6
BOOTPROTO=none
ONBOOT=yes
NETMASK=255.255.255.0
IPADDR=192.168.1.10
USERCTL=yes
 See Fedora Docs  
Reboot and confirm the change  ip addr show dev enp0s31f6 
 
  
Install and enable Samba
 This also sets the firewall to allow access to Samba from other computers. See Fedora Docs for more. There is also a useful article in Fedora magazine.   
Install the Samba software and open access to it through the local machine firewall so other machines (even those on your local network) can access it.   sudo -i 
 dnf install samba 
 sudo systemctl enable smb --now 
 firewall-cmd --get-active-zones 
 sudo firewall-cmd --permanent --zone=FedoraWorkstation --add-service=samba 
 sudo firewall-cmd --reload 
  
 Do user and group setup. See the private instructions.  
Tell Samba that this is a share  semanage fcontext --add --type "samba_share_t" /fsDisk 
restorecon -R /fsDisk 
  
Configure Samba 
There is no longer a GUI tool for configuring Samba. There was one in the past but it is no longer supported for a variety of reasons (lack of developer support, known bugs, etc). So, you have to manually edit the /etc/samba/smb.conf file. Below is a very simple smb.conf file that will make one share with NO security (everyone can read/write it). I am using this for my private file share that is behind my router. 
 # Run 'testparm' to verify the config is correct after
# you modified it.
#
# The name of the share is in square brackets [],
#   this will be shared as //hostname/sharename
# There are a three exceptions:
#   the [global] section;
#   the [homes] section, that is dynamically set to the username;
#   the [printers] section, same as [homes], but for printers.
#
# path: the physical filesystem path (or device)
# comment: a label on the share, seen on the network.
# read only: disable writing, defaults to true.
#
# Note:
# SMB1 is disabled by default. This means clients without support for SMB2 or
# SMB3 are no longer able to connect to smbd (by default).
#
# BUG!
#	workgroup = SAMBA
#	workgroup = FEDORA
#	security = user
#	passdb backend = tdbsam
#	valid users = %S, %D%w%S

[global]
	server role = standalone server
	workgroup = SAMBA

	log file = /var/log/samba/%m
        log level = 1
	
[fileroot]
        comment = File System Share
        path = /fsDisk
	guest ok = yes
        guest only = yes
	read only = no

	writeable = yes
        browseable = yes
        public = yes
        create mask = 0770
        directory mask = 0770
 
 By default, Samba uses tdbsam for user information. This is based on “TDB” (trivial database). Also by default the workgroup is "SAMBA".  
Make sure SMBv1 is disabled 
See https://www.cisa.gov/uscert/ncas/current-activity/2017/01/16/SMB-Security-Best-Practices 
You can add the following to the [global] section of /etc/samba/smb.conf  client min protocol = SMB2_02 server min protocol = SMB2_02  However, I leave this out if the config file includes the comment that SMBv1 is disabled.  
Some useful links:  https://docs.fedoraproject.org/en-US/quick-docs/samba/ 
https://fedoramagazine.org/fedora-32-simple-local-file-sharing-with-samba/ 
 
  
Mount the Samba Share on a Linux Client
   
Now look for IP addresses of other machines to see what is in use. This should confirm that the static IP we set up above is visible.  dnf install nmap 
nmap -sn 192.168.1.0/24 
nmap -sT -O 192.168.1.0/24 
  
Install the CIFS client software  sudo -i 
dnf install cifs-utils 
 
Make a place to mount the remove server  sudo -i 
mkdir /fileServer 
chmod ugo+rwx /fileServer 
  
Modify your /etc/fstab file. 
WARNING!!!!! Do NOT change any other line in the /etc/fstab file. This can make your system unusable and require a complete new OS install!!!! Only APPEND a new line. You have been warned. //192.168.1.10/fileroot /fileServer cifs guest,vers=3.0,noperm 0 0
 The option noperm in fstab tells the client to not do permission checks. This can expose files on this mount to access by other users on the local client system  
Reload the modified /etc/fstab file to remount all file systems  mount -a 
 
  
Mount the Samba Share on a Windows Client
 I do not have a good fix here. The big problem seems to be the client cannot authenticate to a Samba server that has no password. I have tried changing the registry keys. I have read Microsoft KB notes that say to use "the Local Group Policy Editor (gpedit.msc)". I have also read posts and seen notes saying to use Regedit to add a DWORD named "AllowInsecureGuestAuth" and set its value to 1 under the following keys: 
 HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\LanmanWorkstation\ 
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\LanmanWorkstation\Parameters 
 See the KB https://docs.microsoft.com/en-us/troubleshoot/windows-server/networking/guest-access-in-smb2-is-disabled-by-default Then they say to use File Explorer to right-click "This PC" and in the context menu select "Add a network location". But this doesn't work for me. So, instead I do this: 
  
Mount the server to a local drive through the command line  net use x: \\192.168.1.10\fileroot /user:"" "" 
  
Or mount the server to a local drive through the GUI  Right click "This PC" and select the "Map Network Drive..." 
 
 However, this does NOT survive across reboots. After rebooting, it fails to mount the server again because the user name and password are blank. So, I got a bit frustrated (and I don't use Windows daily) and made a shell script which is on the desktop which I have to run to mount the server. 
net use x: /delete
net use x: \\192.168.1.10\fileroot /user:""  ""
 Yes, there is a better way, and yes I am obviously missing something above. But for now, this will get me through. 
  
Block Access to the SMB Ports from outside the router
 See https://kb.netgear.com/8219/How-to-setup-Inbound-Outbound-firewall-rules-on-NETGEAR-Modem-router-gateways. This will block Internet access to the device but it will be accessible on the LAN to others.  Launch an internet browser from a computer or wireless device that is connected to the network. This will be usually one of these:  http://www.routerlogin.net 
http://www.routerlogin.com 
http://192.168.1.1 
http://192.168.0.1 
http://10.0.0.1 
 
Click "Advanced" tab 
Select the "Security > Block Services" section from the pane on the left 
Under Service Table, click "Add" 
US-CERT recommends that users and administrators consider:  UDP/137 - used by nmbd - incoming UDP datagrams from the local network 
UDP/138 - used by nmbd - incoming UDP datagrams from the local network 
TCP/139 - used by smbd - incoming TCP connections 
TCP/445 - used by smbd - incoming TCP connections 
 
 

 
 Installing and configuring Emacs A few common shortcuts that I personally prefer. The blessing/curse of emacs is that it is so customizable, everyone ends up with a slightly different solution. These are what I have come up with so far, but I am also still trying to tweak it to make it more to my liking. Still, you may not like these design choices. 
When testing a .emacs file, you can always use "M-x load-file" and then enter the file name. This will reload the config file without quitting and restarting the program. 
 
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Emacs Customization
;; Tips and tricks from many sources, collected by Dawson Dean
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Font Size and Type
;;
;; The height is 1/100th of a point, so 100 is a 10pt font.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(set-default-font "DejaVu Sans Mono")
(set-face-attribute 'default nil :height 100)


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Text Colors
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(set-face-foreground 'font-lock-string-face "black")
(set-face-foreground 'font-lock-comment-face "dark green")
(set-face-foreground 'font-lock-comment-delimiter-face "dark green")
(set-face-foreground 'font-lock-function-name-face "black")
(set-face-foreground 'font-lock-variable-name-face "black")
(set-face-foreground 'font-lock-keyword-face "dark blue")
(set-face-foreground 'font-lock-type-face "black")
(set-face-foreground 'font-lock-constant-face "black")
(set-face-foreground 'font-lock-builtin-face "black")
(set-face-foreground 'font-lock-preprocessor-face "black")

;; The color of the mark region
(set-face-attribute 'region nil :background "#BFEFFF")
;; Blue:    0000FF
;; Orange:  FFA000


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Custom Key Bindings
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Ctrl-Z is undo.
(global-set-key (kbd "C-z") 'undo)
(global-set-key (kbd "C-Z") 'undo)

;; Ctrl-/ will goto-line
;; This is totally unique to me, nobody else agrees on this. Lots of people
;; seem to like "Esc-g g" but that's still too many keystrokes for me.
(define-key global-map (kbd "C-/") 'goto-line)

;; I sometimes have the Control key held down while doing other things.
(define-key global-map (kbd "") (kbd ""))
(define-key global-map (kbd "") [Double-Mouse-1])


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Basic Editing
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Shift-click will extend the mark region
(define-key global-map (kbd "") 'mouse-save-then-kill)

;; Typing will replace the currently selected text.
(delete-selection-mode 1)


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Syntax Table Hacking
;; http://www.emacswiki.org/emacs/EmacsSyntaxTable
;;
;; Word operations will not treat "_" as a word-break in C++. This puts
;; the character "_" (which is quoted with ? so it is ?_) in the "word"
;; class of characters (which is identified by "w").
;; Really, we just want to evaluate this:  (modify-syntax-entry ?_ "w")
;; But we add a hook so our customization is not clobbered every time
;; the symbol table is edited.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(add-hook 'text-mode-hook (lambda () (modify-syntax-entry ?_ "w")))
(add-hook 'c-mode-hook (lambda () (modify-syntax-entry ?_ "w")))
(add-hook 'c++-mode-hook (lambda () (modify-syntax-entry ?_ "w")))
(add-hook 'html-mode-hook (lambda () (modify-syntax-entry ?_ "w")))
(add-hook 'xml-mode-hook (lambda () (modify-syntax-entry ?_ "w")))
(add-hook 'java-mode-hook (lambda () (modify-syntax-entry ?_ "w")))
(add-hook 'js-mode-hook (lambda () (modify-syntax-entry ?_ "w")))
(add-hook 'js2-mode-hook (lambda () (modify-syntax-entry ?_ "w")))
(add-hook 'abbrev-mode-hook (lambda () (modify-syntax-entry ?_ "w")))



;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Select the entire buffer
;; This was copied (with some small changes) from:
;; https://www.gnu.org/software/emacs/manual/html_node/eintr/mark_002dwhole_002dbuffer.html
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(defun mark-whole-buffer()
       "Select the entire buffer"
       (interactive)
       (message "mark-whole-buffer!")
        ;; Put point at beginning 
       (push-mark (point))
        ;; Put the mark at end of buffer.
       (push-mark (point-max) nil t)
       (goto-char (point-min))
) ;; defun
(global-set-key (kbd "C-S-A") 'mark-whole-buffer)




;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; CUA Mode
;;
;; This makes Ctl-x cut, Ctl-v paste, and Ctl-C copy.
;; This is what you use in Web browsers, so it makes sense for all applications to
;; share a common convention.
;; http://www.emacswiki.org/emacs/CuaMode
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(cua-mode t)
(transient-mark-mode 1) ;; Default in Emacs 23 and later. Selected region is only active when highlighted
;;(setq cua-auto-tabify-rectangles nil) ;; Don't tabify after rectangle commands
;;(setq cua-keep-region-after-copy t) ;; Standard Windows behaviour



;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Searching: Find, Find-And-Replace, Grep 
;;
;; As I switched back to emacs after years on Microsoft's Visual Studio, I realized
;; that I use search to navigate around a buffer more than Ctl-V and Esc-V or similar
;; things. Here are some functions to find the next and previous instance of the
;; currently selected text.
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Find the next instance of the selected text
(defun forward-search-selection (beg end)
    "Search for the current selection"
    ;; This tells elisp to call this command with the point and mark
    ;; as arguments parameters bound to beg and end
    (interactive "r")

    ;; Save the current selection to a local variable.
    ;; We want to deactivate the mark, so save a private copy first.
    (let (
          (selection (buffer-substring-no-properties beg end))
         )
        ;;(message "selection:%s" selection)
    
        ;; De-activate the current mark region. We will change the mark later
        (deactivate-mark)

        ;; Find the next instance of the string.
        ;; https://www.gnu.org/software/emacs/manual/html_node/eintr/search_002dforward.html#search_002dforward
        ;; search-forward takes 4 arguments:
        ;;      The search pattern
        ;;      Optional - limit of search. nil means end of buffer
        ;;      Optional - how to handle failed search. nil means print a message.
        ;;                   t means return a result
        ;;      Optional - How many instances to find
        (when (search-forward selection nil t)
            ;; If search-forward returned true, then it found a match.
            ;; Select the match. This is nice for user feedback but it also
            ;; lets another search-forward find the next occurrence.
            (setf
                (mark) (match-beginning 0)
                (point) (match-end 0))
        ) ;; when
    ) ;; let
) ;; forward-search-selection
(define-key global-map (kbd "") 'forward-search-selection)



;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Find the previous instance of the selected text
(defun reverse-search-selection (beg end)
    "Search for the current selection"
    ;; This tells elisp to call this command with the point and mark
    ;; as arguments parameters bound to beg and end
    (interactive "r")

    ;; Save the current selection to a local variable.
    ;; We want to deactivate the mark, so save a private copy first.
    (let (
          (selection (buffer-substring-no-properties beg end))
         )
      
        ;; De-activate the current mark region. We will change the mark later
        (deactivate-mark)

        ;; Find the prev instance of the string.
        ;; This works like search-forward except it runs in reverse
        ;; search-backward takes 4 arguments:
        ;;      The search pattern
        ;;      Optional - limit of search. nil means end of buffer
        ;;      Optional - how to handle failed search. nil means print a message.
        ;;                   t means return a result
        ;;      Optional - How many instances to find
        
        (when (search-backward selection nil t)
            ;; If search-forward returned true, then it found a match.
            ;; Select the match. This is nice for user feedback but it also
            ;; lets another search-forward find the next occurrence.
            (setf
                (mark) (match-end 0)
                (point) (match-beginning 0))
        ) ;; when
    ) ;; let
) ;; reverse-search-selection
(define-key global-map (kbd "") 'reverse-search-selection)



;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Replace Text

;; Replace the next instance of the selected text
(defun forward-replace-selection (beg end)
    "Search for the current selection"
    ;; This tells elisp to call this command with the point and mark
    ;; as arguments parameters bound to beg and end
    (interactive "r")

    ;; Save the current selection to a local variable.
    ;; We want to deactivate the mark, so save a private copy first.
    (let (
          (selection (buffer-substring-no-properties beg end))
         )
        ;; (message "forward-replace-selection:%s" selection)
    
        ;; De-activate the current mark region. We will change the mark later
        (deactivate-mark)

        (let (
            (replaceStr (read-from-minibuffer "Replacement: "))
            )
            ;;(message "replaceStr:%s" replaceStr)

            ;; Go to the start of the buffer.
            ;; search-forward will only start at the current position.
            (goto-char (point-min))

            ;; https://www.gnu.org/software/emacs/manual/html_node/elisp/Search-and-Replace.html
            (while (search-forward selection nil t)
                ;; https://www.gnu.org/software/emacs/manual/html_node/elisp/Replacing-Match.html
                ;; replace-match replacement &optional fixedcase literal string subexp
                ;; fixedcase says to not change the case of the replacement text
                ;; to match the text being replaced.
                (replace-match replaceStr t))
        ) ;; let

    ) ;; let
) ;; forward-replace-selection
(define-key global-map (kbd "C-r") 'forward-replace-selection)



;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Grep

;; Find the next instance of the selected text
(defun grep-selection (beg end)
    "Grep for the current selection"
    ;; This tells elisp to call this command with the point and mark
    ;; as arguments parameters bound to beg and end
    (interactive "r")

    ;; Save the current selection to a local variable.
    ;; We want to deactivate the mark, so save a private copy first.
    (let (
          (pattern (buffer-substring-no-properties beg end))
         )
        (message "ddGrep:%s" pattern)
    
        ;; De-activate the current mark region. We will change the mark later
        (deactivate-mark)

        ;; grep-find is a built-in emacs elisp function.
        ;; See: https://www.gnu.org/software/emacs/manual/html_node/emacs/Grep-Searching.html#Grep-Searching
        ;; See: https://www.gnu.org/software/emacs/manual/html_node/emacs/Grep-Searching.html

        ;; The options are the normal command line grep options.
        ;; Here, I use:
        ;;  -e, --regexp=PATTERN      use PATTERN for matching
        ;;  -i, --ignore-case         ignore case distinctions
        ;;  -n, --line-number         print line number with output lines
        ;;  -H, --with-filename       print file name with output lines
        ;;  -R, --recursive           like --directories=recurse, and also follow all symlinks
        ;;
        ;; Some useful topns which are not used now, but may be used later
        ;;  -w, --word-regexp         force PATTERN to match only whole words
        ;;  -x, --line-regexp         force PATTERN to match only whole lines
        ;;  -m, --max-count=NUM       stop after NUM selected lines
        ;;  -h, --no-filename         suppress the file name prefix on output
        ;;  -o, --only-matching       show only the part of a line matching PATTERN
        ;;  --include=FILE_PATTERN    search only files that match FILE_PATTERN
        ;;  -L, --files-without-match print only names of FILEs with no selected lines
        ;;  -l, --files-with-matches  print only names of FILEs with selected lines
        ;;  -T, --initial-tab         make tabs line up (if needed)
        ;;  -B, --before-context=NUM  print NUM lines of leading context
        ;;  -A, --after-context=NUM   print NUM lines of trailing context
        ;;  -C, --context=NUM         print NUM lines of output context
        (grep (concat "grep -i -n -H -R -e \"" (shell-quote-argument pattern) "\" /home/ddean/ddRoot/code"))
    ) ;; let
) ;; grep-selection
(define-key global-map (kbd "") 'grep-selection)




;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Parens and Braces
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Find the matching (open or close) paren
;; This was copied (with some small changes) from:
;; https://www.gnu.org/software/emacs/manual/html_node/efaq/Matching-parentheses.html
(defun find-match-paren (arg)
    "Go to the matching paren if on a paren; otherwise insert %."
    (interactive "p")
    (cond
            ((looking-at "\\s(") (forward-list 1) (backward-char 1))
            ((looking-at "\\s)") (forward-char 1) (backward-list 1))

            ((looking-at "\\s[") (forward-list 1) (backward-char 1))
            ((looking-at "\\s]") (forward-char 1) (backward-list 1))
    ) ;; cond
) ;; defun
(define-key global-map (kbd "C-]") 'find-match-paren)

;; Make braces act like parens, and match opens and closes
(modify-syntax-entry ?{ "(}")
(modify-syntax-entry ?} "){")





;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Tabs and Indentation
;;
;; http://www.emacswiki.org/emacs/IndentationBasics
;; https://stackoverflow.com/questions/344966/improved-tab-in-emacs
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;; Tabs are space characters, not a tab character.
(setq-default indent-tabs-mode nil)

(global-set-key (kbd "TAB") 'tab-to-tab-stop)
(setq default-tab-width 4)
(setq tab-width 4)

;; tab-width is used when DISPLAYING tabs, while tab-stop-list 
;; is needed to determine tab stops when you ADD tabs.
;; From emacs documentation, "The variable tab-stop-list controls these positions. The default value is nil, which means a tab stop every 8 columns."
;;;(setq-default c-basic-offset 4)
(setq tab-stop-list (number-sequence 4 200 4))

;; Be careful. If you set this to newline-and-indent, then emacs
;; will autoindent no matter what you set the autoindent options to.
;;(global-set-key (kbd "RET") 'newline-and-indent)
(global-set-key (kbd "RET") 'newline)

;; Don't use tabs to indent code.
;;;(setq-default indent-tabs-mode nil)

;; Stop emacs from trying to second-guess what it thinks I want.
(when (fboundp 'electric-indent-mode) (electric-indent-mode -1))
;;(setq-default electric-indent-inhibit t)

;; Pasting a newline does not cause an indent.
(global-set-key "\C-j" 'newline)



;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Indenting and Un-Indenting
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(defun shift-region (distance)
  (let ((mark (mark)))
    (save-excursion
      (indent-rigidly (region-beginning) (region-end) distance)
      (push-mark mark t t)
      ;; Tell the command loop not to deactivate the mark
      ;; for transient mark mode
      (setq deactivate-mark nil))))

(defun shift-right ()
  (interactive)
  (shift-region 4))

(defun shift-left ()
  (interactive)
  (shift-region -4))

;; C-[ is equivalent to the escape key on US English keyboards
;; Changing  C-[ will break things like Esc-x
(global-set-key (kbd "C-]") 'shift-right)
(global-set-key (kbd "C-.") 'shift-right)
(global-set-key (kbd "C-,") 'shift-left)




;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; Backup Files
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
(setq backup-directory-alist `(("." . "~/emacsBackupFiles")))

(setq delete-old-versions t
  kept-new-versions 1
  kept-old-versions 1
  version-control t)

;; This will turn off all backup files.
;; (setq make-backup-files nil)





 


 

 
   vi editor
 I used emacs until I went into IDE's. Now that I am back to some linux programming, here are some tips for those times when I do a bit of VI (like when you are running as root and need an editor for a config file). 
 
 Run vi - "vi fileName"  
Enter insert mode - Type "i <RET>". Now any further text you type is entered into the file as data. You can use the arrow keys to move around the file. This command leaves command mode.  
Leave insert mode - Type the <ESC> key. Now you are back in command mode.  
Save changes and exit vi - ":wq <RET>" Type this in command mode  
Exit vi withOUT saving changes - ":q! <RET>" Type this in command mode  
Search for the next occurrence after the cursor of some pattern - "/pattern <RET>" Type this in command mode  
Search for the previous occurrence after the cursor of some pattern - "?pattern <RET>" Type this in command mode  
Find the next occurrence of the pattern - "n <RET>" Type this in command mode  
Save the current file - ":w <RET>" Type this in command mode  
Save the current file to a new file - ":w fileName <RET>" Type this in command mode 
 

 
   Emacs Common Things
 For some reason, I always forget these things. 
 Conditional-Search-Replace M-% string RET newstring RET 
Then, <Space> to replace the current instance, <DEL> to skip the current instance, <RET> to stop search without any more replacements 
 

 
   Burning DVDs on Linux
 I use an online backup service, but I still like to burn my home directory to a DVD every few days. It lets me make my own offsite backups, as well as shuttle my home directory between machines and between Linux and Windows. I know I might be able to use some online service for that, but with more complexity, with a monthly subscription fee, with challenges in portability across operating systems, with a dependency on a third party company that may change their UI or features or costs, and with my data sitting on somebody else's computer which may be secure but is also an inviting target for hackers. On Windows, I just used Roxio, but on Linux, here is a quick and dirty solution. I wrote scripts to do this, so I just run the script to burn an image: 
This uses growisofs, which requires you install 
    yum install dvd+rw-tools
 
Burning a data DVD with a tree of files
     su
    mkisofs -J -R -o /your-temp-directory-name/foo.iso -root your-top-level-dir-name  /your-home-dir
    growisofs -dvd-compat -Z /dev/cdrom=/your-temp-directory-name/foo.iso 
    rm -rf /your-temp-directory-name/foo.iso
 Restoring a Directory from a DVD
     su
    umount /dev/cdrom
    mount -t iso9660   /dev/cdrom   your-temp-directory-name
    rm -r -I   your-home-dir
    cp -r your-temp-directory-name   your-home-dir
    chown -R   your-user:your-group   your-home-dir
    chmod -R   u+rwx  your-home-dir
    umount /dev/cdrom
 Note, these must run as root. Burning VOB files to a Video DVD
 There are several alternatives.  mkisofs -dvd-video -o mydvd.iso -udf /path/to/filedir/ 
This will not skrink, so the .iso file will be 8gb 
genisoimage -dvd-video -v -o DVD.iso DVD 
 

 
   Compiling Linux programs with static libraries
 Linux has adopted the philosophy that programs should be dynamic linked. There are both legal reasons for this (the libraries are built under GPL) and practical. However, suppose you want to compile a program, and then run your program on servers provided by web hosting companies. Your program must be compiled with exactly the same version of the runtime libc as is available on the hosting servers. Do hosting companies guarantee that? Of course not. So, instead your program must be compiled with static libraries. That is the problem I am trying to solve, and here are some notes. 
  Compile your programs with static linking. The compiler uses the flag -static. There are some other flags that I have seen discussed, but in practice I don't need them. These include the flags -Wl -Bstatic, where -Wl sends a flag to the linker and -Bstatic is the static link flag 

 
 Install the static libraries  yum install glibc-static 
yum install libstdc++-static 
 
 
 Key networking system calls do not seem to work for a statically linked program. Specifically, you cannot lookup a network address if you are statically linked because getaddrinfo and even gethostname do not work. It seems that the name resolution library runs different code depending on host-specific preferences, like whether to use DNS or other network infrastructure. So, rather than writing 1 program that can call out to different local name resolver services (like, via a local pipe or system call), the C library is hard-compiled with the diffreent sources. This means that libc cannot call gethostbyname in a portable way. Instead, you must dynamically link with the local glibc on each different machine. If you really need to run the static glibc, then you cannot use this call. 
 

 
  Installing and configuring mySQL
 Installation
 I use Fedora, which uses dnf and yum, and the best guide I found (granted after only a cursory look) is at www.if-not-true-then-false.com/2010/install-mysql-on-fedora-centos-red-hat-rhel  

 
  Installing and configuring Apache
 See https://fedoraproject.org/wiki/Apache_HTTP_Server  Install Apache   su 
 dnf install httpd 
To have the server start at each boot: systemctl enable httpd.service 
To start the server now: systemctl start httpd.service 
 
 Configuration  GUI Configuration tool: /usr/bin/system-config-httpd 
Manual edit config files. emacs /etc/httpd/conf/httpd.conf 
 
 
 

 
  Using CSS "position" attributes for HTML Layout
 
 
  Many HTML elements may use CSS to control where they are positioned on a page. This is done with a "position" attribute, that may have two values: "absolute" or "relative". For example: 
 style="position:absolute; left:0px; top:0px;" 
style="position:relative; left:0px; top:0px;" 
  These can be confusing, because they use the terms "absolute" and "relative" to place an element in a position in relation to the "normal position of that element in the HTML layout", and NOT necessarily in relation to another element. So, the browser first lays out an HTML document, which assigns every element in the document to a position on the page. This initial position is referred to as the element's position in the "document flow". Once the browser has completed this initial layout step, then the CSS position attributes may override each element's position and place the element in a different place. 
 "Relative" means place the element at some offset in relation to where it would normally go in the HTML laytout. So, for example, if a typical HTML page would place an element at x=100,y=200, and the element had an attribute 
 style="position:relative; left:50px; top:75px;"
 then the element would be placed at x=150,y=275.  "Absolute" means place the element at some "absolute" position, and just ignore where it would normally go in the HTML laytout. So, for example, if a typical HTML page would place an element at x=100,y=200, and the element had an attribute 
style="position:absolute; left:50px; top:75px;"
 then the element would be placed at x=50,y=75.  However, the confusing part is that an "absolute" coordinate is still in relation to somethng. It may be in relation to the bottom-left corner of the HTML page, but it may also be in relation to a containing element, like a div element. So, "position:absolute" means an absolute position compared to the flow of the document but still relative to the position of the parent HTML element that contains the element being moved.  

 
  Installing Raspberry Pi
 Installation with Linux
  Run lsblk to see which devices are NOT the SD card. This will print a list of devices. 
Plug an SD card into the linux box - I use a USB-SD-reader. 
Run "lsblk" again. The USB HDMI is cometimes sdb, but beware. That can differ with different devices. 
sudo -i 
parted /dev/sdb - or whatever the device name of the SD card is.  (parted) mklabel msdos 
(parted) mkpart primary fat32 1MiB 100% 
(parted) set 1 boot on 
 
mkfs.vfat /dev/sdb1 
Ctrl-D 
Download the latest noobs OS software from downloads.raspberrypi.org/noobs 
Mount the device. One way to do this is to open Files, which will automount the new device. 
cd ~/Downloads 
unzip NOOBS_v2_8_2.zip -d /run/media/userName/xxxxxx - where userName is your name and XXXX is the volume name of the SD drive 
Plug in the SD card, a USB mouse, a USB Keyboard, a HDMI monitor into the Pi and connect a powersupply. 
Plug the power supply in, and the Pi should boot. It will install an OS from your SD card 
 Some handy references:  https://www.raspberrypi.org/app/uploads/2012/04/quick-start-guide-v2_1.pdf 
https://www.pcworld.com/article/3176712/linux/how-to-format-an-sd-card-in-linux.html 
 Copying Files from Linux to a Pi
  Configure the Pi to accept SSH connections.  sudo systemctl enable ssh 
sudo systemctl start ssh 
 Or, try this:  On desktop, select menu "Preferences>Raspberry Pi Configuration" 
Select the Interfaces tab 
Select "Enabled" next to SSH 
Select the "OK" button, and the Pi will reboot 
 
On the Pi, open a terminal window and run "ifconfig". Next to the wlan0 entry, get the IP address 
To copy from Linux to Pi: scp file.txt pi@xxx.xxx.xxx.xxx:destinationDir/ 
To copy from Pi to Linux: scp file.txt pi@xxx.xxx.xxx.xxx: 
 Some handy references:  https://stackoverflow.com/questions/41318597/ssh-connection-refused-on-raspberry-pi 
 Cross-compiling on Linux and Running on Pi
 I am not doing this yet. Currently, I am just maintaining source code on my dev box and copying it to a Pi and compiling it there.  yum install apt-get install git rsync cmake 
Note that ia32-libs is no longer supported. 
 Some handy references:  https://stackoverflow.com/questions/19162072/how-to-install-the-raspberry-pi-cross-compiler-on-my-linux-host-machine

Table of Contents

Overview

Installation

Creating repositories

Modifying and Committing Files

Getting Updates

Status Commands

Delete/Undo Changes

GDB in Emacs

GDB Commands

Using gprof

Mount the NAS on a Linux Client

Format and mount a new disk

Set a Static IP Address for your Server

Install and enable Samba

Mount the Samba Share on a Linux Client

Mount the Samba Share on a Windows Client

Block Access to the SMB Ports from outside the router

Burning a data DVD with a tree of files

Restoring a Directory from a DVD

Burning VOB files to a Video DVD

Installation

Installation with Linux

Copying Files from Linux to a Pi

Cross-compiling on Linux and Running on Pi

`Status Commands`

`Delete/Undo Changes`