'./file' meaning in python & shell script

Chowroc · 12-12-2005, 08:40 PM

I found the meanings of './file' are different in shell script & python, while in python, it means the same directory the program runs, and in shell, it means the current directory the user is when he/she runs the script.

How can I get the python effect in shell script? When I run the script anywhere, it can find the 'subscripts' that it calls correctly?

Thanks.

randyding · 12-13-2005, 12:09 AM

could do this as the first thing in the bash script

cd `dirname $0`

then from elsewhere in the script ./someprog will run someprog in the same directory the script is located.
Note this may still not work exactly as you would expect if the script was run through a symbolic link.

Chowroc · 12-28-2005, 12:11 AM

well, it's a good idea. Thank you very much.

And I have made a mistake: Both shell & python have the same meaning of "./file", but I cat get the absolute pathname by os module in python, just like `dirname $0`:

import os
import sys
location = os.path.abspath(os.path.dirname(sys.argv[0]))

Chowroc · 12-28-2005, 08:44 PM

I think there are still some problems to use `dirname $0` if you don't execute the script with absolute pathname.

Any good idea?

randyding · 12-28-2005, 09:05 PM

Actually its important to do this in the script...
1. wd="`pwd`"
2. cd "`dirname "$0"`"
3. programdir="`pwd`"
4. cd "$wd"
This will eliminate the problem of executing the script with a relative path.
`pwd` will always begin with a '/', root path.
So far I haven't found a better way to get the program directory, there could very well be. Also remember if the program is run through a symbolic link then the program directory will end up being the directory the symbolic link is in.

Hko · 12-29-2005, 03:53 AM

That will not work when the script is started with:
bash script.sh
./script.sh

randyding · 12-29-2005, 09:52 PM

Hi,
I'm not sure exactly what won't work,
its probably just my misunderstanding of what the OP wants.
However, all my tests show it does work even the two cases
you showed me above.
It was my understanding his desire was to know the location
of the script, and the code I posted seems to do that,
am I missing something... just wanted to know.

Code:

[0 randyd@entropy ~]$ cat t.sh
#!/bin/sh

wd="`pwd`"
cd "`dirname "$0"`"
programdir="`pwd`"
cd "$wd"

echo "$programdir"

[0 randyd@entropy ~]$ ./t.sh
/home/randyd
[0 randyd@entropy ~]$ bash t.sh
/home/randyd
[0 randyd@entropy ~]$ cd ..
[0 randyd@entropy home]$ randyd/t.sh
/home/randyd
[0 randyd@entropy home]$

Chowroc · 12-30-2005, 03:32 AM

I think this is a good method for shell script. Although it's not so convenient, it does work. Thank you.