Shell Productivity

Shell Productivity — Quick Reference

history — Command History

history                       # list all previous commands
history 20                    # last 20 commands
history | grep git            # search history
!!                            # re-run last command
!42                           # re-run command #42 from history
!git                          # re-run last command starting with "git"
!$                            # last argument of previous command
Ctrl+R                        # interactive reverse search through history

alias — Command Shortcuts

alias ll='ls -lah'            # define alias
alias gs='git status'
alias ..='cd ..'
alias grep='grep --color=auto'

unalias ll                    # remove alias
alias                         # list all aliases

To make aliases permanent, add them to ~/.bashrc or ~/.zshrc.

source — Load a Script into Current Shell

source ~/.bashrc              # reload shell config
source .env                   # load env file into current shell
. ~/.bashrc                   # same as source (shorthand)

tee — Write to File AND stdout

command | tee output.txt              # write to file and print to terminal
command | tee -a output.txt           # append instead of overwrite
command | tee file.txt | grep ERROR   # branch the pipe

Useful when you want to save output while still seeing it live.

watch — Repeat a Command on Interval

watch -n 2 df -h              # run df -h every 2 seconds
watch -n 1 'ps aux | grep node'   # monitor a process
watch -d free -h              # highlight changes between runs

set — Shell Script Behavior

Put at the top of bash scripts:

set -e          # exit immediately on any error
set -u          # treat unset variables as errors
set -x          # print each command before running (debug mode)
set -o pipefail # catch errors in piped commands (set -e misses these)

# All together (recommended for scripts)
set -euo pipefail

Keyboard Shortcuts (bash / zsh)

Shortcut	Action
`Ctrl+R`	Reverse search history
`Ctrl+C`	Kill current process
`Ctrl+Z`	Suspend current process
`Ctrl+D`	Exit / EOF
`Ctrl+L`	Clear screen
`Ctrl+A`	Move cursor to start of line
`Ctrl+E`	Move cursor to end of line
`Ctrl+W`	Delete word before cursor
`Ctrl+U`	Delete from cursor to start of line
`Ctrl+K`	Delete from cursor to end of line
`Alt+.`	Insert last argument of previous command
`Tab`	Autocomplete

Redirection & Pipes

command > file.txt            # stdout to file (overwrite)
command >> file.txt           # stdout to file (append)
command 2> err.txt            # stderr to file
command &> file.txt           # stdout + stderr to file
command 2>/dev/null           # discard stderr
command1 | command2           # pipe stdout of cmd1 to cmd2
command1 |& command2          # pipe stdout + stderr
tee file.txt                  # write to file AND pass through

Brace Expansion

mkdir -p src/{components,utils,hooks}        # create multiple dirs
touch file{1..5}.txt                         # file1.txt ... file5.txt
cp config.yaml config.yaml.bak              # quick backup
mv file.{txt,md}                            # rename extension
echo {a,b,c}.log                            # a.log b.log c.log

Parameter Expansion

file="report.tar.gz"

${file%.*}       # remove shortest suffix match  → report.tar
${file%%.*}      # remove longest suffix match   → report
${file#*.}       # remove shortest prefix match  → tar.gz
${file##*.}      # remove longest prefix match   → gz
${file/old/new}  # replace first match
${file//old/new} # replace all matches
${#file}         # length of string              → 13
${file:-default} # use default if unset

Useful One-Liners

# Run last command as sudo
sudo !!

# Create a timestamped backup
cp config.yaml config.yaml.$(date +%Y%m%d)

# Run a command every time a file changes (using watch)
watch -n 1 cat output.txt

# Find and kill a process on a port
kill $(lsof -ti :8080)

# Print lines 10-20 of a file
sed -n '10,20p' file.txt

# Count unique IPs in an access log
awk '{print $1}' access.log | sort | uniq -c | sort -rn | head -10

# Monitor disk usage every 5 seconds
watch -n 5 df -h

Tips

set -euo pipefail at the top of every bash script — catches most silent failures.
Ctrl+R is the fastest way to re-run a long command you used recently.
Store alias definitions in ~/.bashrc (bash) or ~/.zshrc (zsh) to persist across sessions.
tee is invaluable for debugging pipelines — branch output to a file without breaking the chain.

← Linux