Does bash have a hook that is run before executing a command?

Posted by Gilles on Super User See other posts from Super User or by Gilles
Published on 2010-08-14T11:09:20Z Indexed on 2012/03/22 11:33 UTC
Read the original article Hit count: 281

Filed under:

bash

|

hook

In bash, can I arrange for a function to be executed just before running a command?

There is $PROMPT_COMMAND, which is executed before showing a prompt, i.e., just after running a command.

Bash's $PROMPT_COMMAND is analogous to zsh's precmd function; so what I'm looking for is a bash equivalent to zsh's preexec.

Example applications: set your terminal title to the command being executed; automatically add time before every command.

© Super User or respective owner

Related posts about bash

launching a program from bash causes bash to go to new prompt

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
When I run a program from the console, e.g. me@box:~$ firefox I expect the console to log error messages (I think this is std out or std err?) and other items from the program, firefox in this case. But today I notice that bash just opens the program and goes to a new prompt, e.g. me@box:~$… >>> More
How to debug a .bash_profile

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I was updating my .bash_profile, and unfortunetly I made a few updates and now I am getting: env: bash: No such file or directory env: bash: No such file or directory env: bash: No such file or directory env: bash: No such file or directory env: bash: No such file or directory -bash: tar: command… >>> More
Every command fails with "command not found" after changing .bash_profile?

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I was updating my .bash_profile, and unfortunetly I made a few updates and now I am getting: env: bash: No such file or directory env: bash: No such file or directory env: bash: No such file or directory env: bash: No such file or directory env: bash: No such file or directory -bash: tar: command… >>> More
Is there any fundamental difference between piping in mac and linux?

as seen on Super User - Search for 'Super User'
ps -e | grep bash sample output from a linux machine: 1128 pts/14 00:00:00 bash 7491 pts/7 00:00:00 bash 12651 pts/14 00:00:00 bash 16145 pts/2 00:00:00 bash sample output from a mac machine: 58352 ttys000 0:00.09 login -pfl username /bin/bash -c exec -la bash /bin/bash 58353 ttys000… >>> More
why is $0 set to -bash?

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
First login process name seems to be set to "-bash", but if I subshell then it becomes "bash". for example: root@nowere:~# echo $0 -bash root@nowere:~# bash root@nowere:~# echo $0 bash -bash is causing some scripts to fail, such as . /usr/share/debconf/confmodule exec /usr/share/debconf/frontend… >>> More

Related posts about hook

qwebview in pyside after packaged with pyinstaller goes wrong

as seen on Stack Overflow - Search for 'Stack Overflow'
Here's my code import sys from PySide.QtCore import * from PySide.QtGui import * from PySide.QtWebKit import * from encodings import * from codecs import * class BrowserWindow( QWidget ): def __init__( self, parent=None ): QWidget.__init__( self, parent ) self.Setup() … >>> More
Apache & SVN on Ubuntu - Post-commit hook fails silently, pre-commit hook “Permission Denied”

as seen on Server Fault - Search for 'Server Fault'
I've been struggling for the past couple days to get post-commit email notifications working on my SVN server (running via HTTP with Apache2 on Ubuntu 9.10). SVN commits work fine, but for some reason the hooks are not being properly executed. Here are the configuration settings: - Users access the… >>> More
Apache & SVN on Ubuntu - Post-commit hook fails silently, pre-commit hook "Permission Denied"

as seen on Stack Overflow - Search for 'Stack Overflow'
I've been struggling for the past couple days to get post-commit email notifications working on my SVN server (running via HTTP with Apache2 on Ubuntu 9.10). SVN commits work fine, but for some reason the hooks are not being properly executed. Here are the configuration settings: - Users access the… >>> More
How do I pass a custom field to a hook (Invision Power Board [ipb] / PHP)

as seen on Stack Overflow - Search for 'Stack Overflow'
A long shot but here's hoping someone has some experience coding PHP hooks for Invisions Power Board forum. I'm attempting to code a status addition and the PHP works fine on it's own, it's the passing of the IPB's reference to my hook that is the issue. I.E. You setup a custom field in your forum… >>> More
Why does my laptop resume immediately after suspend?

as seen on Ask Ubuntu - Search for 'Ask Ubuntu'
I seem to be having some problem with suspend mode. Every time I try to suspend my laptop, it just locks the screen. Or maybe it successfully suspends just to resume only an instant after. What could cause such a behaviour? I'm running 32-bit Ubuntu 12.04 with the 3.2.0-25 kernel on a HP dv5-1178er… >>> More