https://github.com/codenameyau/dotfiles
:neckbeard: My knowledge of all things linux, servers, and bash with config files
https://github.com/codenameyau/dotfiles
bash bashrc caddy command-line config curl dotfiles git gitconfig githook linux nginx provisioning raspberry-pi scripts shell unix vimrc vscode
Last synced: 4 months ago
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:neckbeard: My knowledge of all things linux, servers, and bash with config files
- Host: GitHub
- URL: https://github.com/codenameyau/dotfiles
- Owner: codenameyau
- License: gpl-3.0
- Created: 2014-05-16T14:25:33.000Z (over 11 years ago)
- Default Branch: master
- Last Pushed: 2023-10-16T04:06:28.000Z (about 2 years ago)
- Last Synced: 2025-03-27T04:51:24.769Z (7 months ago)
- Topics: bash, bashrc, caddy, command-line, config, curl, dotfiles, git, gitconfig, githook, linux, nginx, provisioning, raspberry-pi, scripts, shell, unix, vimrc, vscode
- Language: Shell
- Homepage:
- Size: 347 KB
- Stars: 19
- Watchers: 5
- Forks: 13
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
## Helpful Resources
- Official GNU reference: https://www.gnu.org/software/bash/manual/html_node/index.html
- Bash Guide for Beginners: https://www.tldp.org/LDP/Bash-Beginners-Guide/html/
- Bash Cheatsheet: https://mywiki.wooledge.org/BashSheet
## Table of Contents
- [Helpful Resources](#helpful-resources)
- [Table of Contents](#table-of-contents)
- [Running Scripts from Anywhere](#running-scripts-from-anywhere)
- [Bin Executable](#bin-executable)
- [Symbolic Link](#symbolic-link)
- [Aliases](#aliases)
- [Extend Path](#extend-path)
- [Script Configurations](#script-configurations)
- [Bash safe mode](#bash-safe-mode)
- [Bash configurations](#bash-configurations)
- [Brace Expansion](#brace-expansion)
- [Variable Expansion](#variable-expansion)
- [String interpolation](#string-interpolation)
- [Default values](#default-values)
- [Pattern matching](#pattern-matching)
- [Regex group pattern matching](#regex-group-pattern-matching)
- [Arithmetic Expressions](#arithmetic-expressions)
- [Compound Commands](#compound-commands)
- [Grouping Statements](#grouping-statements)
- [Sub Shells](#sub-shells)
- [Command Groups](#command-groups)
- [Networks](#networks)
- [Ports](#ports)
- [Nifty Terminal Commands](#nifty-terminal-commands)
- [Generate Timestamps](#generate-timestamps)
- [Set Operations](#set-operations)
- [Miscellaneous](#miscellaneous)
- [Config Files](#config-files)
- [Colors](#colors)
- [Debugging Scripts](#debugging-scripts)
## Running Scripts from Anywhere
First you will need executable permission to run a script.
```bash
# Check to see what permissions files have.
ls -la
# Grant user executable permission.
sudo chmod u+x script.sh
# Then run the script.
./script.sh
```
### Bin Executable
Add the script to your local bin directory with executable permission.
```bash
# Usually bin executables do not have file extensions.
sudo chmod u+x script
# Copy file to user's local binaries folder.
sudo cp script /usr/local/bin/
```
### Symbolic Link
https://stackoverflow.com/questions/1951742/how-to-symlink-a-file-in-linux
```bash
sudo chmod u+x
# Create a new symbolic link (will fail if already exist).
sudo ln -s /usr/local/bin/
# Create or update symbolic link.
sudo ln -sf /usr/local/bin/
# Example
sudo ln -s /opt/android-studio/bin/studio.sh /usr/local/bin/android-studio
# Example with cwd
sudo ln -s "$(cwd)/sherlock.py" /usr/local/bin/sherlock
```
### Aliases
You can create an alias in your `.bashrc`
```bash
alias =''
```
### Extend Path
You can also add any directory to be part of the bash executable path: `$PATH`
```bash
# Add the following line in your `.bash_profile`.
export PATH="":$PATH
# Example
export PATH="~/Workspace/dotfiles/bin":$PATH
```
## Script Configurations
Use `set -o` to turn on a feature and `set +o` to turn it off.
### Bash safe mode
```bash
# Enable bash safe mode.
set -euo pipefail
```
```bash
# Exit script if you try to use an uninitialized variable.
set -o nounset
# Exit script if a statement returns a non-true return value.
set -o errexit
# Use the error of the first failure rather than last error in pipe.
set -o pipefail
```
### Bash configurations
```bash
# Export any variables that are defined.
set -o allexport
# Enable bash history.
set -o history
```
## Brace Expansion
- https://unix.stackexchange.com/questions/6035/when-do-you-use-brace-expansion
```bash
# Rename file (no spaces between commas).
mv myfile.{js,jsx}
# Create files with different extension.
touch myfile.{html,css,js,test.js,stories.js}
# Show output of the cartesian product.
echo {a,b,c}/{1,2,3} | xargs -n1
echo {1..10}/{1..10} | xargs -n1
# Create cartesian product of directories.
mkdir -p ./{ComponentA,ComponentB}/{test,stories}
mkdir -p ./{1..5}/{1..5}
```
## Variable Expansion
- https://mywiki.wooledge.org/BashFAQ/100
- http://tldp.org/LDP/abs/html/variable-expansion.html
- https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html
### String interpolation
```bash
# String interpolation with variables.
echo "I want to eat $fruit"
> I want to eat orange
```
### Default values
```bash
# Initialize variable with default value.
fruit=${1:-'orange'}
echo "I want to eat ${fruit}s"
> I want to eat oranges
```
### Pattern matching
```bash
# Extracting user and repo using pattern matching from beginning (#).
url='https://github.com/codenameyau/intro-to-bash'
echo "${url#*//*/}"
> codenameyau/intro-to-bash
# Extracting repo using greedy pattern matching from beginning (##).
url='https://github.com/codenameyau/intro-to-bash'
echo "${url##*/}"
> intro-to-bash
# Extracting user profile using pattern matching from end (%).
url='https://github.com/codenameyau/intro-to-bash'
echo "${url%/*}"
> https://github.com/codenameyau
# Extracting origin using pattern matching from end (%).
url='https://github.com/codenameyau/intro-to-bash'
echo "${url%/*/*}"
> https://github.com
# Extracting protocol using greedy pattern matching from end (%%).
url='https://github.com/codenameyau/intro-to-bash'
echo "${url%%://*}"
> https
```
### Regex group pattern matching
```bash
# Capturing substring in regex group match.
string="origin https://github.com/USERNAME/REPOSITORY.git (fetch)"
# Capture matched substring USERNAME
echo $(expr "$string" : .*github.com/'\(.*\)'/)
> USERNAME
# Capture matched substring REPOSITORY
echo $(expr "$string" : .*/'\(.*\).git')
> REPOSITORY
```
## Arithmetic Expressions
- Tutorial: https://mywiki.wooledge.org/ArithmeticExpression
- Full reference: http://wiki.bash-hackers.org/syntax/arith_expr
```bash
# Wrap expression with double parens to specify math context.
echo $((1 + 1))
> 2
echo $((3 < 2))
> 0
echo $((1 < 2))
> 1
# Using for loop. Spaces are allowed for assignment.
for ((i = 0; i < 10; i++)); do echo "$1"; done
```
## Compound Commands
- https://mywiki.wooledge.org/BashGuide/CompoundCommands
- https://mywiki.wooledge.org/BashGuide/TestsAndConditionals#Grouping_Statements
### Grouping Statements
You can use short circuiting with guard `&&` and
default `||` statements for basic command grouping.
```bash
# Will exit the shell if cd exists.
cd /tmp && exit 1
# Will exit the shell if cd does not exist.
cd /tmp || exit 1
```
### Sub Shells
This will launch the commands inside the parenthesis in subshell where variables have their own scope and will disappear once the command is complete or exits.
```bash
# The current directory $CWD variable will not be affected.
(cd /tmp || exit 1; date > timestamp)
```
### Command Groups
You can group commands with `{}` to run a series of commands whose
final output could be used. This shares the same variables as the
current session.
```bash
{command_1; command_2; command_3} | command_4
```
## Networks
### Ports
Run this command kill a process running on specific port.
```bash
lsof -t -i :8000
kill $(lsof -t -i :8000)
```
Run this command to see a list of open ports on a system.
```bash
# Show tcp, udp, listening ports, pid, numeric hosts, ipv4
sudo netstat -tulpn4
```
## Nifty Terminal Commands
### Generate Timestamps
https://stackoverflow.com/questions/1204669/how-can-i-generate-unix-timestamps
```bash
# Timestamp: Thu Dec 28 10:44:45 EST 2017
date
# Timestamp: 1514475851 (seconds)
date +%s
# Timestamp: 1514476017560 (milliseconds)
date +%s%3N
```
### Set Operations
These operations must have files sorted first.
```bash
# Get lines common to both files.
comm -12 file1 file2
# Read from std-in, sort, get lines in common, and copy to clipboard.
cat | sort | comm -13 - s1 | pbcopy
# Get lines only found in file1.
comm -23 file1 file2
# Sort files as well.
comm -13 <(sort file1) <(sort file2)
comm -23 <(sort file1) <(sort file2)
```
### Rerunning commands
```sh
# Rerun the previous command with sudo.
sudo !!
# Rurun the previous command with substitutions.
^before^after^
```
## Miscellaneous
### Config Files
Your program's configuration files are stored here. They are not removed by apt purge
and may often contain unnecessary application data.
```
cd ~/./config
```
### Colors
https://stackoverflow.com/questions/5947742/how-to-change-the-output-color-of-echo-in-linux
```bash
Black 0;30 Dark Gray 1;30
Red 0;31 Light Red 1;31
Green 0;32 Light Green 1;32
Brown/Orange 0;33 Yellow 1;33
Blue 0;34 Light Blue 1;34
Purple 0;35 Light Purple 1;35
Cyan 0;36 Light Cyan 1;36
Light Gray 0;37 White 1;37
```
```bash
# Reset colors
Color_Off='\033[0m' # Text Reset
# Regular colors
Black='\033[0;30m' # Black
Red='\033[0;31m' # Red
Green='\033[0;32m' # Green
Yellow='\033[0;33m' # Yellow
Blue='\033[0;34m' # Blue
Purple='\033[0;35m' # Purple
Cyan='\033[0;36m' # Cyan
White='\033[0;37m' # White
# Bold
BBlack='\033[1;30m' # Black
BRed='\033[1;31m' # Red
BGreen='\033[1;32m' # Green
BYellow='\033[1;33m' # Yellow
BBlue='\033[1;34m' # Blue
BPurple='\033[1;35m' # Purple
BCyan='\033[1;36m' # Cyan
BWhite='\033[1;37m' # White
# Underline
UBlack='\033[4;30m' # Black
URed='\033[4;31m' # Red
UGreen='\033[4;32m' # Green
UYellow='\033[4;33m' # Yellow
UBlue='\033[4;34m' # Blue
UPurple='\033[4;35m' # Purple
UCyan='\033[4;36m' # Cyan
UWhite='\033[4;37m' # White
```
### Debugging Scripts
- [Guide to bash debugging](https://mywiki.wooledge.org/BashGuide/Practices#Debugging)
- [Always quote variables](https://mywiki.wooledge.org/BashGuide/Practices#Quoting)
**Method 1:** Run your script with the `-x` flag.
```bash
$ bash -x myscript.sh
```
**Method 2:** Modify the script's interpreter directive to include the `-x` flag.
```bash
#!/bin/bash -x
```
**Method 3:** Selectively debug sections of code.
```bash
#!/bin/bash
# Turn on debugging.
set -x
# Turn off debugging.
set +x
```