Retrive the file system position where a bash script is saved [duplicate]

Question

Possible Duplicate:
In the bash script how do I know the script file name?

I often need the file system of a bash script to reference other needed resources. Normally use the following code in line after the shebang line. It sets a variable called 'scriptPos' contains the current path of the scripts

scriptPos=${0%/*}

It works fine, but is there something more intuitive to replace the shell expansion?

It contains a similar solution like my way. The problem is I forget the syntax every time and only take it with copy and paste from script to script :-D — OkieOth
– OkieOth, Commented Sep 10, 2012 at 15:09

Thor · Accepted Answer · 2012-09-10 15:02:47Z

1

There's dirname but it requires a fork:

scriptPos=$(dirname "$0")

answered Sep 10, 2012 at 15:02

Thor

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2 Comments

tripleee Over a year ago

... and isn't necessarily more intuitive.

Thor Over a year ago

@user1651840: try strace -e execve -f with dirname in a script. @tripleee: well I seem to remember this one, while I always have check the parameter expansion.

chepner · Accepted Answer · 2012-09-11 12:03:39Z

0

One option is

scriptPos=$(dirname $0)

which comes at the cost of an extra process, but is more self-descriptive. If the script is in the current directly, the output differs (for the better, in my opinion):

#!/bin/bash
scriptPos=$(dirname $0)

echo '$0:' $0
echo 'dirname:' $scriptPos
echo 'expansion:' ${0%/*}

$ bash tmp.bash
$0: tmp.bash
dirname: .
expansion: tmp.bash

UPDATE: An attempt to address the shortcomings pointed out by jm666.

#!/bin/bash
scriptPos=$( v=$(readlink "$0") && echo $(dirname "$v") || echo $(dirname "$0") )

edited Sep 11, 2012 at 12:03

answered Sep 10, 2012 at 15:05

chepner

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1 Comment

clt60 Over a year ago

this will not work 1) with symlinked script. (will show the dirname for the symlink). 2) for the relative path will show "../../dir", not the place of the script in the filesystem.

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