Bash keeps a history of the commands you type in and saves them to
~/.bash_history. These commands can be accessed in many ways and there are a lot of configuration related on how they are saved. I’ll cover some basic functionality here.
Event Designators (
From MAN Pages
An event designator is a reference to a command line entry in the history list. Unless the reference is absolute, events are relative to the current position in the history list.
For the different examples below, assume we are running it against the same command (
netstat -an | grep ':22'). This is to help you visualize the differences between each of the event designators.
Repeating the last command that starts with
You can run the most recent command starting with
string by using
$ !netstat netstat -an | grep ':22' tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN tcp6 0 0 :::22000 :::* LISTEN tcp6 0 0 :::22
$ ls my_file.txt .rw-r--r-- 0 victor users 18 Oct 11:35 my_file.txt $ ls my_folder drwxr-xr-x - victor users 18 Oct 11:35 my_folder $ !ls ls my_folder drwxr-xr-x - victor users 18 Oct 11:35 my_folder
Tip: you can use the
:p option to print the command instead of running it
$ !netstat:p netstat -an | grep ':22'
Repeating the same command with
As you may already know, the
!! can be used for repeating the same command.
$ echo !! echo netstat -an | grep ':22'
This is useful when you forget to use
sudo on a command that requires sudo access.
$ systemctl daemon-reload Failed to reload daemon: Access denied $ sudo !! sudo systemctl daemon-reload [sudo] password for victor:
Re-using the last argument with
Another very useful option is the
!$, which provides quick access to the last argument in a command.
$ echo !$ echo ':22'
This can come in handy if you need to repeat the last argument with another command.
$ touch my_new_script.sh $ vim !$ vim my_new_script.sh
$ mkdir myfolder $ cd !$
fc allows you to open commands in your history with an editor, modify the commands and then execute the modified version. It will use your default editor (as per
$EDITOR), so make sure that is set.
Some common usage for
fc -l- List your last commands
fc n- Edit the n command
fc -1- Edit the last command
fc 20 22- Edit commands 20 to 22
On this section we talk a little bit about some of the configuration available for your Bash history.
Adds time to each command in history
# Sets up time for history export HISTTIMEFORMAT="+%Y/%m/%d %T "
$ history | tail -n 10 949 +2019/03/11 00:32:53 ssh seedbox 950 +2019/03/11 16:05:53 cd .config/polybar 951 +2019/03/11 16:05:56 ./launch.sh 952 +2019/03/11 17:49:38 lolbanner victor 953 +2019/03/11 17:53:10 lolbanner test 954 +2019/03/11 17:53:11 psg checkupdates 955 +2019/03/11 17:53:11 clear 956 +2019/03/11 17:53:11 echo hello 1 957 +2019/03/11 17:53:11 history 958 +2019/03/11 18:10:01 history | tail -n 10
Avoid duplicate entries
# Avoid duplicates export HISTCONTROL=ignoredups:erasedups
This comes in handy if you run multiple terminal emulators simultaneously. By default, the latest closed terminal emulator will overwrite history from the other windows. With this setting, changes are appended making sure all commands are saved to history.
# When the shell exits, append to the history file instead of overwriting it shopt -s histappend