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General

filter output keeping the first line

df -h | awk 'NR==1||/var$/' 
Filesystem                                     Size  Used Avail Use% Mounted on
/dev/mapper/system-var                         9.8G  6.2G  3.2G  67% /var

path info

file="/home/user/file.inc.php"
basename=${file##*/}       # file.inc.php
filename=${basename%.*}    # file.inc
extension=${file##*.}      # php
dirname=${file%/*}         # /home/user

SSH authentication by key

cd ~/.ssh
ssh-keygen
ssh-copy-id -i ~/.ssh/id_rsa.pub remote.host.com
ssh-add
ssh remote.host.com
If username has a “@” symbol then use the following: 
ssh -l user@example.com example.com
mkdir .ssh
touch .ssh/authorized_keys
exit
cat ~/.ssh/id_rsa.pub | ssh -l user@example.com example.com 'cat >> .ssh/authorized_keys'
chmod 700 .ssh
chmod 400 .ssh/authorized_keys
ssh -l user@example.com example.com

Bash prompt w/ path and colors

~/.bash_profile:

Local (green) 

export PS1="\[\e[0;38;05;15m\][\[\e[0;38;05;47m\]\u\[\e[0;38;05;15m\]@\[\e[0;38;05;208m\]\h:\[\e[0;38;05;111m\]\w\[\e[0;38;05;15m\]]\\$ \[\e[0m\]"
Remote (yellow): 
export PS1="\[\e[0;38;05;15m\][\[\e[0;38;05;226m\]\u\[\e[0;38;05;15m\]@\[\e[0;38;05;226m\]\h:\[\e[0;38;05;180m\]\w\[\e[0;38;05;15m\]]\\$ \[\e[0m\]"
Root (red and yellow) 
export PS1="\[\e[0;38;05;15m\][\[\e[0;38;05;196m\]\u\[\e[0;38;05;15m\]@\[\e[0;38;05;226m\]\h:\[\e[0;38;05;180m\]\w\[\e[0;38;05;15m\]]\\$ \[\e[0m\]"

Colors

for i in {0..255}; do echo -e "\e[38;05;${i}m${i}"; done | column -c 80 -s '  '; echo -e "\e[m"

for code in $(seq -w 0 255); do for attr in 0 1; do printf "%s-%03s %bTest%b\n" "${attr}" "${code}" "\e[${attr};38;05;${code}m" "\e[m"; done; done | column -c $((COLUMNS*2))

Vim

~/.vimrc 

set nocompatible
set backspace=2
set tabstop=4
set expandtab
set number

Load additional php.ini when run php from terminal

  1. Add the following line into ~/.bashrc file:

    export PHP_INI_SCAN_DIR=":$HOME/etc/php70"

  2. Put additional config into ~/etc/php70/php.ini, e.g:

    memory_limit = -1

  3. Run the command #1 or re-login terminal

  4. Check ini paths:

    php --ini

  5. Check memory limit:

    $ php -i | grep memory_limit
memory_limit => -1 => -1

More info on php.net

Convert DOS to Unix newlines in current directory excluding .git directory

find . -type f -not -path './.git/*' -print0 | xargs -0 dos2unix

Use custom SSH port with rsync/ssh/scp/sshfs

rsync -avz -e "ssh -p 2244" --exclude=var user@server.com:/html/ .
ssh user@server.com -p 2244
scp -P 2244 user@server.com:/html/website_db.sql .
sshfs user@server.com:/html -p 2244 server.com

Upload multiple files w/o file name duplication

scp {,user@example.com:~/}public_html/index.php
scp {,user@example.com:~/}public_html/.htaccess
scp {,user@example.com:~/}public_html/images/logo.png
scp {,user@example.com:~/}public_html/js/jquery.js

FIX permissions

find . -type f -exec chmod 640 {} \;
find . -type d -exec chmod 750 {} \;

Statistics

Find # of code lines in directory

(find . -type f -name '*.php' -print0 | xargs -0 cat) | wc -l

Date/Time format

date +%Y-%m-%d\ %H:%M:%S\ %:z     # 2020-04-02 21:53:08 +03:00
date -Iseconds                    # 2020-04-02T23:02:42+03:00

Ctrl+C Hook

trap ctrl_c INT

function ctrl_c() {
    echo "Triggered CTRL+C event"
}

Process start end time

ps -eo pid,lstart,etime,args | sed '1p;/php/!d'

Diff large files

diff -y --suppress-common-lines --speed-large-files file1 file2
Source: unix.stackexchange.com

  1. How to parse command line arguments