grep
    # Search Within Files using Regular Expressions
    # Syntax: grep <options> <search-term> <filename>
    #
    # -i ignore case
    # -n show line numbers
    # -R recursive
    # -I ignore binary files
    # -l print out file names instead
    # -P Perl syntax \d \w \s
    # -E extended syntax [[:digit:]] [[:alpha:]] [[:space:]]
    # {2} exactly, {1,3} from to, {2,} two or more
    # --include=*.py search only in .py files.

# Search word needle in file haystack.txt
grep 'needle' haystack.txt

# Search in .py files of current and all subdirectories, ignore case, print filenames only
grep -Rli --include=*.py 'needle' *

find
    # Find Files or Directories Based On Name 
    # Syntax: find <location> <options>
    #
    # -type f=search only files, d=search only directories
    # -name name
    # -iname caseinsensitive name
    
# List all file names and directory names containing needle
find . -name 'needle'

# List only file names containing needle
find . -type f -name 'needle'

# List all files ending in .py
find . -type f -name "*.py"

# List all files ending in .py, containing needle, hide error messages
find . -type f -name "*.py" -exec grep -li 'needle' {} +

# Recursively count number of files in all subdirectories
find . -type f | wc -l

# Unzip files
find . -name '*.zip' -print0 | xargs -0 -I {} -P 10 unzip -qq {}

# Unzip files without going into subdirectories
find . -maxdepth 1 -name '*.zip' -print0 | xargs -0 -I {} -P 10 unzip -qq {}

# Creating
ssh-keygen -t rsa -b 4096 -N "" -C "" -f keyname
mv keyname* ~/.ssh

# Setting access rights
chmod 700 ~/.ssh && chmod 600 ~/.ssh/*

# ~/.ssh/config
Host github
HostName github.com
User git
IdentityFile ~/.ssh/keyname

# This logs into the server, and copies the public key to it.
ssh-copy-id -i ~/.ssh/keyname user@remote_machine

# Checking the ssh procesd
ssh -T [email protected]
eval $(ssh-agent -s)
ssh-add ~/.ssh/keyname
ssh -T [email protected]

# Finding out which linux you are using
uname -m && cat /etc/*release

# Bulk renaming of files
rename 's/ch0/ch/gi' *.tiff

# Make output of df and du human readable
alias df='df -h'
alias du='du -h'

# Count files in directory
alias fcount='ls -1 | wc -l'

# Disable "Save workspace" promt when closing R
alias R='R --no-save'