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Bash Readline Quick Reference

Overview

Readline is the library used by Bash (and many other programs) for command-line editing. It provides powerful keyboard shortcuts for navigation, editing, and history management.

Why Master Readline: - Works in Bash, Python REPL, MySQL CLI, etc. - Faster than using arrow keys - Essential for SSH sessions with laggy connections - Reduces hand movement (stay on home row) - Works consistently across Unix/Linux systems

Check Readline Bindings: 

bind -p | grep -v "^#" | grep -v "not bound"

1. Cursor Movement

Basic Navigation

Ctrl+a - Move to beginning of line (A = start of alphabet)
Ctrl+e - Move to end of line (E = end)
Ctrl+b - Move back one character (B = back)
Ctrl+f - Move forward one character (F = forward)

Alt+b - Move back one word
Alt+f - Move forward one word

Example: 

$ ls -la /var/log/application.log
^ cursor here

Ctrl+a → $ ls -la /var/log/application.log
^ cursor at start

Ctrl+e → $ ls -la /var/log/application.log
^ cursor at end

Alt+b → $ ls -la /var/log/application.log
^ cursor moved back one word

Mnemonic: - Ctrl = character movement - Alt (or Esc) = word movement

2. Editing Commands

Delete/Kill

Ctrl+d - Delete character under cursor (D = delete)
Ctrl+h - Delete character before cursor (same as Backspace)

Ctrl+k - Kill (cut) from cursor to end of line (K = kill)
Ctrl+u - Kill from cursor to beginning of line
Ctrl+w - Kill word before cursor (W = word)

Alt+d - Kill word after cursor
Alt+Backspace - Kill word before cursor (alternative to Ctrl+w)

Examples:

# Delete from cursor to end of line
$ echo "This is a long command with many arguments"
^ cursor here
Ctrl+k → $ echo "
(text after cursor is killed/cut)

# Delete from cursor to start of line
$ git commit -m "Initial commit"
^ cursor here
Ctrl+u → $ "Initial commit"
(text before cursor is killed)

# Delete previous word
$ kubectl get pods --namespace production
^ cursor here
Ctrl+w → $ kubectl get pods --namespace
(word "production" is killed)

Paste (Yank)

Ctrl+y - Yank (paste) last killed text
Alt+y - Rotate through kill ring (after Ctrl+y)

Example: 

$ echo "delete this" keep this
^ select "delete this"
Ctrl+u → $ keep this
$ echo "paste here: "
Ctrl+y → $ echo "paste here: delete this"

Transpose

Ctrl+t - Transpose (swap) characters (T = transpose)
Alt+t - Transpose words

Example: 

# Fix typo "teh" → "the"
$ teh quick brown
^ cursor between e and h
Ctrl+t → $ the quick brown
(h and e swapped)

# Swap words
$ brown quick fox
^ cursor on "quick"
Alt+t → $ quick brown fox

Case Manipulation

Alt+u - Uppercase word from cursor (U = uppercase)
Alt+l - Lowercase word from cursor (L = lowercase)
Alt+c - Capitalize word from cursor (C = capitalize)

Example: 

$ echo hello world
^ cursor here
Alt+u → $ echo HELLO world

$ echo HELLO WORLD
^ cursor here
Alt+l → $ echo hello WORLD

$ echo hello world
^ cursor here
Alt+c → $ echo Hello world

3. Command History

Basic History Navigation

Ctrl+p - Previous command in history (P = previous, same as Up arrow)
Ctrl+n - Next command in history (N = next, same as Down arrow)

Ctrl+r - Reverse incremental search (R = reverse)
Ctrl+s - Forward incremental search (S = search)
(Note: Ctrl+s may be disabled by flow control, see troubleshooting)

Ctrl+g - Escape from history search mode
Ctrl+j or Enter - Execute found command

Example: 

# Search command history
Ctrl+r
(reverse-i-search)`': 

# Type "git"
(reverse-i-search)`git': git status

# Press Ctrl+r again to find next match
(reverse-i-search)`git': git commit -m "Fix bug"

# Press Enter to execute or Ctrl+g to cancel

History Expansion

!! - Repeat last command
!$ - Last argument of previous command
!^ - First argument of previous command
!* - All arguments of previous command
!n - Execute command number n from history
!-n - Execute command n lines back

Alt+. - Insert last argument of previous command
Alt+_ - Same as Alt+.

Examples:

$ ls /var/log/application.log
$ vim !$
# Expands to: vim /var/log/application.log

$ echo arg1 arg2 arg3
$ echo !^
# Expands to: echo arg1

$ sudo !!
# Repeat last command with sudo

$ cat /etc/hosts
$ vim Alt+.
# Inserts: vim /etc/hosts

History Commands

history - Show command history
history 20 - Show last 20 commands
history -c - Clear history
!123 - Execute command 123 from history
!ssh - Execute last command starting with "ssh"
!?pattern - Execute last command containing "pattern"

4. Completion

Tab Completion

Tab - Complete command/filename
Tab Tab - Show all possible completions

Alt+? - List possible completions (same as Tab Tab)
Alt+* - Insert all possible completions

Examples:

$ cd /var/lo[Tab]
$ cd /var/log/

$ systemctl sta[Tab][Tab]
start status stop

$ git comm[Tab]
$ git commit

$ ls *.tx[Tab]
$ ls *.txt

Command-Specific Completion

Bash supports programmable completion for many commands:

# Git branch completion
$ git checkout ma[Tab]
$ git checkout main

# Kubernetes completion
$ kubectl get po[Tab]
$ kubectl get pods

# SSH hostname completion (from ~/.ssh/config and ~/.ssh/known_hosts)
$ ssh serv[Tab]
$ ssh server01

Enable kubectl completion: 

source <(kubectl completion bash)

5. Advanced Editing

Undo and Redo

Ctrl+_ or Ctrl+x Ctrl+u - Undo last edit
Alt+r - Revert line (undo all changes)

Clear Screen and Line

Ctrl+l - Clear screen (L = clear, same as `clear` command)
Ctrl+c - Cancel current command / interrupt
Ctrl+d - Exit shell (if line is empty) / EOF (D = done)
Ctrl+z - Suspend current process (put in background)

Quoted Insert

Ctrl+v - Insert next character literally (V = verbatim)
Ctrl+q - Same as Ctrl+v (Q = quote)

Example: 

# Insert a Tab character literally (instead of completion)
$ echo "hello[Ctrl+v][Tab]world"
$ echo "hello   world"
^ actual tab character

# Insert Ctrl+C literally
$ echo "Press [Ctrl+v][Ctrl+c] to cancel"
$ echo "Press ^C to cancel"

6. Command Line Editing Modes

Readline supports two editing modes: Emacs (default) and Vi.

Check Current Mode

set -o | grep -E 'emacs|vi'

Switch Modes

# Switch to Vi mode
set -o vi

# Switch back to Emacs mode (default)
set -o emacs

Vi Mode

In Vi mode, you start in Insert mode and can press Esc to enter Normal mode.

Normal Mode Commands: 

h/j/k/l - Left/Down/Up/Right (like Vim)
w/b - Forward/Backward word
0/$ - Start/End of line
x - Delete character
dw - Delete word
dd - Delete line
yy - Yank line
p - Paste
u - Undo
/ - Search history forward
? - Search history backward
n - Next search result

Example: 

$ git commit -m "Initial commit"
Esc → Enter normal mode
0 → Move to start of line
w → Move forward one word
dw → Delete "commit"
i → Back to insert mode
push → Type "push"
$ git push -m "Initial commit"

Note: Most SRE/DevOps professionals use Emacs mode (default) for consistency across systems.

7. Macros and Custom Bindings

View Current Bindings

# List all key bindings
bind -p

# Search for specific binding
bind -p | grep '\\C-a'

# List function names
bind -l

Create Custom Bindings

Add to ~/.inputrc:

# Create ~/.inputrc if it doesn't exist
touch ~/.inputrc

Example bindings:

# Use up/down arrows for history search (like fish shell)
"\e[A": history-search-backward
"\e[B": history-search-forward

# Alt+l to lowercase current word
"\el": downcase-word

# Ctrl+x Ctrl+e to edit command in $EDITOR
"\C-x\C-e": edit-and-execute-command

# Show all completions without double-tab
set show-all-if-ambiguous on

# Ignore case in completions
set completion-ignore-case on

# Show completion list immediately
set show-all-if-unmodified on

# Color completion by file type
set colored-stats on

# Mark symlinked directories
set mark-symlinked-directories on

Reload inputrc: 

bind -f ~/.inputrc
# or restart shell

Useful Custom Bindings

# Ctrl+x Ctrl+e: Edit command in $EDITOR (Vim/Nano)
# Useful for complex multi-line commands
"\C-x\C-e": edit-and-execute-command

Example: 

$ for i in {1..10}; do echo $i; done[Ctrl+x Ctrl+e]
# Opens command in Vim, edit, save (:wq), executes

8. Practical SRE/DevOps Workflows

Quick Directory Navigation

# Jump to previous directory
$ cd -

# Jump to home directory
$ cd ~

# Jump to directory in $CDPATH
export CDPATH=.:~:/var/log:/etc
$ cd nginx # Jumps to /etc/nginx if it exists

Readline shortcuts: 

$ cd /var/log/application/backend/service/logs
Ctrl+w Ctrl+w Ctrl+w → $ cd /var/log/application

Efficient Command Building

# Reuse last argument
$ ls /var/log/app.log
$ vim [Alt+.]
# Becomes: vim /var/log/app.log

# Build command incrementally
$ kubectl get pods -n production
Ctrl+a → move to start
$ watch [Space]
# Becomes: watch kubectl get pods -n production

Fix Typos Quickly

$ git statu
Ctrl+a → Move to start
Alt+f → Move to "statu"
$ git status

# Or use history substitution
$ ^statu^status^
# Runs: git status

Search and Execute

# Find that long kubectl command from history
Ctrl+r
(reverse-i-search)`kubectl apply': kubectl apply -f deployment.yaml

# Edit before executing
Ctrl+a → Move to start
Alt+f → Move forward to filename
Ctrl+k → Kill to end
new-deployment.yaml → Type new filename
# Becomes: kubectl apply -f new-deployment.yaml

Kill Ring Rotation

$ echo "first text"
Ctrl+u → Kill line
$ echo "second text"
Ctrl+u → Kill line
$ echo "third text"
Ctrl+u → Kill line

$ echo ""
Ctrl+y → Pastes: "third text"
Alt+y → Rotates to: "second text"
Alt+y → Rotates to: "first text"

9. History Management

History Configuration

Add to ~/.bashrc:

# Increase history size
export HISTSIZE=10000 # In-memory history
export HISTFILESIZE=20000 # On-disk history

# Avoid duplicates
export HISTCONTROL=ignoredups:erasedups

# Append to history, don't overwrite
shopt -s histappend

# Save multi-line commands as one entry
shopt -s cmdhist

# Timestamp in history
export HISTTIMEFORMAT="%F %T "

# Ignore common commands
export HISTIGNORE="ls:ll:cd:pwd:bg:fg:history"

# Save history after each command
PROMPT_COMMAND="history -a; history -c; history -r; $PROMPT_COMMAND"

History Search Patterns

# Search for all git commands
$ history | grep git

# Execute specific history item
$ !1234

# Execute last kubectl command
$ !kubectl

# Search and confirm before executing
$ !git:p # Prints command, doesn't execute
$ !! # Then execute if correct

10. Troubleshooting

Ctrl+S Freezes Terminal (Flow Control)

Problem: Pressing Ctrl+s freezes the terminal.

Cause: Ctrl+s activates XON/XOFF flow control.

Solution: 

# Disable flow control (add to ~/.bashrc)
stty -ixon

# If frozen, press Ctrl+q to unfreeze

Backspace Produces ^? or ^H

Problem: Backspace key doesn't work correctly.

Solution: 

# Add to ~/.inputrc
"\C-h": backward-delete-char
"\C-?": backward-delete-char

Alt Key Not Working (Sends Escape Sequences)

Problem: Alt+b, Alt+f don't work.

Solution: 

# Terminal emulator settings (check):
# - "Use Option as Meta key" (iTerm2/Terminal.app on Mac)
# - "Alt sends Escape" (PuTTY on Windows)

# Or use Esc key instead of Alt
# Press Esc, then b (two separate keystrokes)

Tab Completion Not Working

Problem: Tab completion missing or incomplete.

Solution: 

# Install bash-completion (Fedora/RHEL)
sudo dnf install bash-completion

# Enable in ~/.bashrc
if [ -f /etc/bash_completion ]; then
. /etc/bash_completion
fi

History Not Persisting

Problem: Command history is lost between sessions.

Solution: 

# Check HISTFILE
echo $HISTFILE
# Should be: /home/username/.bash_history

# Ensure it's writable
ls -la ~/.bash_history

# Force write history
history -a

11. Readline in Other Programs

Readline shortcuts work in many CLI programs:

Python REPL

$ python3
>>> import sys
>>> sys.^A^E^K

MySQL CLI

mysql> SELECT * FROM users WHERE username = 'admin';
^A^E^B^B^B^B^K

PostgreSQL (psql)

psql=# \d users
^P (previous command)

Redis CLI

127.0.0.1:6379> GET mykey
^A^F^F^F (move forward)

Node.js REPL

> console.log("Hello");
^U (clear line)

12. Cheat Sheet Summary

Ctrl+a - Beginning of line
Ctrl+e - End of line
Ctrl+b - Back one character
Ctrl+f - Forward one character
Alt+b - Back one word
Alt+f - Forward one word

Editing

Ctrl+d - Delete character under cursor
Ctrl+h - Delete character before cursor
Ctrl+k - Kill to end of line
Ctrl+u - Kill to beginning of line
Ctrl+w - Kill previous word
Alt+d - Kill next word
Ctrl+y - Yank (paste) killed text
Ctrl+t - Transpose characters
Alt+t - Transpose words

History

Ctrl+p - Previous command
Ctrl+n - Next command
Ctrl+r - Reverse search
Ctrl+g - Cancel search
!! - Repeat last command
!$ - Last argument
Alt+. - Insert last argument

Control

Ctrl+l - Clear screen
Ctrl+c - Cancel/Interrupt
Ctrl+d - Exit (if line empty)
Ctrl+z - Suspend process
Tab - Complete
Tab Tab - Show completions

13. Practice Exercises

Exercise 1: Navigation Drills 

# Type this command, then practice navigation:
$ kubectl apply -f /path/to/kubernetes/manifests/deployment.yaml

# Practice:
# 1. Move to beginning (Ctrl+a)
# 2. Move forward 3 words (Alt+f x3)
# 3. Move to end (Ctrl+e)
# 4. Move back 2 words (Alt+b x2)

Exercise 2: Quick Edits 

# Type:
$ docker run -it --name mycontainer ubuntu:latest

# Change "run" to "exec":
# Ctrl+a, Alt+f, Ctrl+w, type "exec"

# Change container name:
# Alt+f x3, Ctrl+k, type "newcontainer"

Exercise 3: History Mastery 

# Execute several git commands:
$ git status
$ git add .
$ git commit -m "Fix"
$ git push origin main

# Now:
# 1. Search for "commit" (Ctrl+r, type "commit")
# 2. Change message (Ctrl+e, Ctrl+w, Ctrl+w, type new message)
# 3. Execute

14. Configuration Template

~/.inputrc (recommended settings):

# Use vi or emacs mode (choose one)
set editing-mode emacs
# set editing-mode vi

# Show completion immediately
set show-all-if-ambiguous on
set show-all-if-unmodified on

# Case-insensitive completion
set completion-ignore-case on

# Color completion by type
set colored-stats on
set colored-completion-prefix on

# Show symlink directories with /
set mark-symlinked-directories on

# Show file type indicators
set visible-stats on

# Single tab for completion
set show-all-if-ambiguous on

# Pager for long completion lists
set page-completions on

# Up/Down arrow history search
"\e[A": history-search-backward
"\e[B": history-search-forward

# Ctrl+arrows for word movement
"\e[1;5C": forward-word
"\e[1;5D": backward-word

# Edit command in editor
"\C-x\C-e": edit-and-execute-command

~/.bashrc (recommended settings):

# History size
export HISTSIZE=10000
export HISTFILESIZE=20000

# History control
export HISTCONTROL=ignoredups:erasedups
shopt -s histappend
shopt -s cmdhist

# Timestamp
export HISTTIMEFORMAT="%F %T "

# Ignore common commands
export HISTIGNORE="ls:ll:cd:pwd:bg:fg:history:clear"

# Save after each command
PROMPT_COMMAND="history -a; $PROMPT_COMMAND"

# Enable bash completion
if [ -f /etc/bash_completion ]; then
. /etc/bash_completion
fi

# Disable flow control (enable Ctrl+s search)
stty -ixon

References

Official Documentation: - Readline Manual: https://tiswww.case.edu/php/chet/readline/rltop.html - Bash Manual: https://www.gnu.org/software/bash/manual/ - man readline - man bash

Cheat Sheets: - https://readline.kablamo.org/emacs.html - https://www.bigsmoke.us/readline/shortcuts

Interactive Practice: - https://www.shortcutfoo.com/app/dojos/command-line

Updated: 2026-05-23 Author: Documentation Team Use Case: Command-line efficiency, SRE, DevOps, System Administration