How to command history is saved in Linux
Command history is saved in .bash_history file by history command.
Customization :
1 - Location
You can change history file location of by overwriting HISTFILE
2 - Time
By default, history doesn't store the time of command execution you can provide HISTTIMEFORMAT to store it
3 - History limit
The default size of history is 500 you can increase by overwriting the following variables
# .bash_history file events limit
export HISTFILESIZE=20000
# history command events limit
export HISTSIZE=10000
Productivity Hack: Use CTRL + R to cycle through history to reuse previously executed command rather than finding by clicking up arrow repeatedly.
Problem: If you are using multiple ssh or tmux sessions, and CTRL + R won't display other sessions command because history is not dumped in the file unless a session is closed gracefully.
There is also the chance of losing history on abruptly closing sessions.
Hack: http://northernmost.org/blog/flush-bash_history-after-each-command/
export PROMPT_COMMAND='history -a'
Explanation:
history -a appends the current history buffer in .bash_history file
The value of the variable PROMPT_COMMAND is examined just before Bash prints each primary prompt (PS1).
PS1 is the primary prompt which is displayed before each command
[ash-ishh@xBot ~]$ echo $PS1
[\u@\h \W]\$
If PROMPT_COMMAND is set and has a non-null value, then the value is executed just as if it had been typed on the command line.
List of possible escape sequences: https://www.gnu.org/software/bash/manual/html_node/Controlling-the-Prompt.html
Command history is saved in .bash_history file by history command.
Customization :
1 - Location
You can change history file location of by overwriting HISTFILE
2 - Time
By default, history doesn't store the time of command execution you can provide HISTTIMEFORMAT to store it
# for storing the date in history in %Y-%M-%D %HH:%MM:%SS
export HISTTIMEFORMAT="%F %T: "
3 - History limit
The default size of history is 500 you can increase by overwriting the following variables
# .bash_history file events limit
export HISTFILESIZE=20000
# history command events limit
export HISTSIZE=10000
Productivity Hack: Use CTRL + R to cycle through history to reuse previously executed command rather than finding by clicking up arrow repeatedly.
Problem: If you are using multiple ssh or tmux sessions, and CTRL + R won't display other sessions command because history is not dumped in the file unless a session is closed gracefully.
There is also the chance of losing history on abruptly closing sessions.
Hack: http://northernmost.org/blog/flush-bash_history-after-each-command/
export PROMPT_COMMAND='history -a'
Explanation:
history -a appends the current history buffer in .bash_history file
The value of the variable PROMPT_COMMAND is examined just before Bash prints each primary prompt (PS1).
PS1 is the primary prompt which is displayed before each command
[ash-ishh@xBot ~]$ echo $PS1
[\u@\h \W]\$
If PROMPT_COMMAND is set and has a non-null value, then the value is executed just as if it had been typed on the command line.
List of possible escape sequences: https://www.gnu.org/software/bash/manual/html_node/Controlling-the-Prompt.html
