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Old 01-30-2012, 01:38 PM   #1
Daravon
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Registered: Mar 2006
Posts: 170

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using cd in bash script


I want to write a script to change directory, and list the destination directory's contents. Basically an alias that does cd and then ls.

So I wrote a script:

Code:
#!/bin/bash

cd $@

ls
This does not have the expected behavior. When I run this script with my /media directory, it spits out the contents of the /media directory as requested, but when the script finishes, I am not cd'd to that directory. Apparently the shell forks a new shell when it runs the script and returns me to my current shell when it's finished.

How can I write a script to cd?

Also, I've noticed that I cannot do
Code:
which myscript | cd
Any insight as to why is appreciated.
 
Old 01-30-2012, 02:25 PM   #2
Tinkster
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You got the first assessment correct.

The 2nd won't work because cd is a bash-built-in.

A quick work-around is to make your script a function.
Code:
function huh
{
  cd $@
  ls
}
To make this "permanent" just add it to your ~/.bashrc

Cheers,
Tink
 
Old 01-30-2012, 03:13 PM   #3
MTK358
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Quote:
Originally Posted by Daravon View Post
How can I write a script to cd?
You can't.

The only way you can do it is by running the script using the "source" command, which runs the script as if you typed the lines into the current shell.
 
Old 01-31-2012, 10:39 AM   #4
David the H.
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As discovered, the only way to get the directory to change in the current environment is to run the cd command in the current environment. A script can't do that. Only a typed command, sourced command, or function can.

As for why this doesn't work:
Code:
which myscript | cd
Pipes connect the stdout of command A to the stdin of command B. But cd isn't a command capable of reading from stdin. In addition, which outputs the path to the script with the filename attached. You'd have to strip it down to the path only before it could be used as input for cd.
 
  


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