Backtracking with bash

April 01, 2003

I was working with linux quite a bit today, and frequently changing between directories, when I wondered if there was a way to go back to the directory I was in previously.

Turns out there is a way:

 cd ~-
So if I was doing something like this:
[pete@bigred /]$ cd /etc
[pete@bigred etc]$ cd /usr/local
[pete@bigred local]$ cd ~-
[pete@bigred etc]$ pwd
If you want to create a command so you don't have to type ~- you can create an alias:
alias cdb='cd ~-'
This ~- thing works great if you only need to go back one directory, but what if you wanted to go back two directories. Continuing the last code sample:
[pete@bigred etc]$ cd ~-
[pete@bigred local]$ cd ~-
[pete@bigred etc]$ pwd
We are back to /etc and not / our starting point. What I want is something that keeps a history of the directories I've been to.

It turns out that the Bash (the "Bourne again shell") has a directory stack builtin. Three command line tools for manipulating the stack are avaliable dirs, pushd, and popd. More info about the directory stack in bash here.

If we pushd a directory onto the directory stack, we can retreive the top of the stack using dirs +1. I tried setting up some aliases to get it to work the way I wanted:

alias cdd='pushd'
alias cdb='cd `dirs +1`'
Those worked a bit, but I ran into a lot of problems, especially when in the home directory. Also when you run pushd, popd, or dirs it always prints the contents of the stack, I don't know how to suppress that. So I figured I would post it here, and see if anyone can come up with a solution, or if anyone knows of a better way of going about this.

Isn't it funny how software developers will spend hours of time trying to save a few seconds of their future time.

3 people found this page useful, what do you think?


cd - works. I don't think you need cd ~-.
You can suppress the output redirecting the output to /dev/null e.g. pushd <dir-name> >> /dev/null popd >> /dev/null
You can use small script from which defines 1-7 dots commands: $/usr/local/share> ... sh[Tab] $/usr/share>
I was Googling for this and ended up writing these: function cd { if [ -n "$1" ]; then pushd $1 > /dev/null else pushd $HOME > /dev/null fi } alias bd='popd > /dev/null' This transparently replaces the cd bash built-in. Note that it doesn't support the -L or -P options, but I've never heard of anyone using those, and anyway they'd be pretty easy to do. Of course, you can use a different name if you don't want to overwrite the default functionality. You do have to use a function for cd to get the redirection right, AFAIK, an alias won't cut it (since bash doesn't replace parameters in aliases).
The above function definition did not work for me, but fixed by adding semicolons:
function cd { if [ -n "$1" ]; then pushd $1 > /dev/null; else pushd $HOME > /dev/null; fi; }

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