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Command History: Don't Retype Everything

Your terminal remembers everything you type. Use that memory.

Here's the thing: History saves time. Reuse commands. Don't retype. Work faster.

Basic History​

View History​

history                           # All commands
history | less                    # Page by page
history | grep "pattern"          # Search history
history | tail -20                # Last 20

My take: history shows what you've done. Search it. Reuse it.

↑ (Up arrow)                      # Previous command
↓ (Down arrow)                    # Next command
Ctrl+R                            # Reverse search

My take: Arrow keys navigate. Ctrl+R searches. Use both.

History Shortcuts​

Reuse Last Command​

!!                                # Last command

Real example:

$ sudo apt update
$ !!                              # Runs: sudo apt update

My take: !! reruns last command. Useful when you forget sudo.

Reuse by Number​

!42                               # Command #42 from history

My take: Rarely used. But useful when you know the number.

Reuse by Pattern​

!git                              # Last command starting with "git"
!?pattern                         # Last command containing "pattern"

Real example:

$ git status
$ git commit -m "fix"
$ !git                            # Runs: git commit -m "fix"

My take: !git runs last git command. Useful for repeating similar commands.

Fix Last Command​

^old^new                          # Replace old with new

Real example:

$ sudo apt updte                  # Typo
$ ^updte^update                   # Fixes and runs: sudo apt update

My take: Fix typos quickly. ^old^new is magic.

Last Argument​

!$                                # Last argument of previous command

Real example:

$ ls /var/log
$ cd !$                           # cd /var/log

My take: !$ is the last argument. Useful for chaining commands.

Ctrl+R                            # Start search
# Type pattern
# Press Ctrl+R to find next
# Press Enter to run

Real example:

# Press Ctrl+R
# Type "nginx"
# Finds: sudo systemctl restart nginx
# Press Enter to run

My take: Ctrl+R is powerful. Search history interactively. Use it.

Aliases: Your Own Shortcuts​

alias ll='ls -la'
alias la='ls -A'
alias ..='cd ..'
alias ...='cd ../..'

Add to ~/.bashrc:

echo "alias ll='ls -la'" >> ~/.bashrc
source ~/.bashrc

My take: Create aliases for commands you use often. Saves typing.

Common Aliases​

alias ll='ls -la'
alias la='ls -A'
alias l='ls -CF'
alias ..='cd ..'
alias ...='cd ../..'
alias grep='grep --color=auto'
alias fgrep='fgrep --color=auto'
alias egrep='egrep --color=auto'

My take: These are common. Use them. Or create your own.

History Configuration​

# In ~/.bashrc
HISTSIZE=10000                     # History size
HISTFILESIZE=20000                 # History file size
HISTCONTROL=ignoredups            # Ignore duplicates
HISTCONTROL=ignoreboth             # Ignore duplicates and commands starting with space

My take: Increase history size. Keep more commands. Useful.

Common Mistakes (I've Made These)​

  1. Not using history: Retyping commands. Use history. Save time.

  2. Not using Ctrl+R: Searching manually. Use Ctrl+R. It's faster.

  3. Not creating aliases: Typing long commands. Create aliases. Save typing.

  4. Forgetting !!: Retyping with sudo. Use !!. It's faster.

  5. Not configuring history: Default size is small. Increase it.

Real-World Examples​

Rerun with sudo​

apt update                        # Forgot sudo
sudo !!                           # Runs: sudo apt update

Fix Typo​

sudo apt instll nginx             # Typo
^instll^install                   # Fixes: sudo apt install nginx

Chain Commands​

ls /var/log
cd !$                             # cd /var/log

What's Next?​

Now that you can use history, you work faster. Or learn about Text Processing to work with files.

Personal note: When I started, I'd retype everything. Then I learned history. Now I reuse commands constantly. History saves hours. Learn it. Use it.