bash, where am I script

rednuht · 08-14-2006, 02:36 PM

if I have a bash script that references a directory that exists within the folder the script resides in then I call the script from somewhere else how can I know where I am to reference said directory ?

I want the the script to do something like

Code:

installedDir=`pwd`
dataDir=$installedDir"/data"
-do something with $dataDir

If I run it from . the script works fine, but if I change to a different directory and then sh /PATH/TO/SCRIPT/script.sh then $installDir is set to where I am when I ran the script not where the script is and so can not find the data folder.

I have the annoying feeling that this is just not possible and I will have to hardcode $installDir and force people to install the script in a known location.

I tried adding

Code:

cd .

but that uses the initial starting folder not the location of the script
I also examined the results of

Code:

set

executed inside the script, nothing even close to useful.

unSpawn · 08-14-2006, 03:36 PM

Since not everyone has a "realpath" Bash loadable module or binary (Busybox for instance has) and readlink (which uses realpath syscall) doesn't work on proc you could try:

Code:

a=($(stat -c %N /proc/$$/fd/255)); s=${a[2]}
n=$[${#s}-2]; echo "I'm here: ${s:1:$n}"

If there's a more elegant solution I would definately be interested.

david_ross · 08-14-2006, 04:21 PM

Couldn't you just temporarily change directory?

Code:

WD=`pwd`
cd ${0%/*}
installedDir=`pwd`
cd $WD

unSpawn · 08-14-2006, 04:36 PM

No external binaries. Definately way better.

soggycornflake · 08-15-2006, 12:23 PM

Why do you need to change directory? Wouldn't

Code:

installedDir=${0%/*}

suffice?

david_ross · 08-15-2006, 01:33 PM

The idea of changing the directory was to guarantee getting the full path incase the script changed directory half way through.

soggycornflake · 08-17-2006, 09:17 AM

Ah, because ${0%/*} is not necessarily an absolute path. Gotcha.

jlliagre · 08-17-2006, 09:58 AM

I'm using that:

Code:

installedDir=$(cd $(dirname $0);pwd)

rednuht · 08-23-2006, 03:17 PM

I added a condition to check if the script was being run from the same folder otherwise the result ended up being the script name plus "data"

Code:

installDir=${0%/*}
if [ $installDir = $0 ]; then
  installDir="."
fi