Shell Programming and Scripting

Hi,

I am pretty new to unix.
Lets say i have a program(run_program) that will call another file function(functiona, in same directory):

hence, inside that run_program. i will just call "functiona xx xx" to refer and use that function. this run ok until i run this program from another folder.
it always say it cannot find the functiona?

Why this happened?

Check your path variable by using echo $PATH . In this see if there is any instance of '.' (dot). If there is (and I think that there will be), then that is the source of your problem.

When the shell executes any command it looks for the full path of the command from the variable $PATH. Then the command is executed using the fork and exec mechanism.
Now I will use the example provided by you to explain:
Assume that you are in the directory /maldini/sh. The value of the '.' in the path is also /maldini/sh (pwd). Now when you run run_program, it runs with pwd as /maldini/sh. When the call to functiona is reached, the shell looks for the script in all the directories in the $PATH variable. Since functiona is also in /maldini/sh directory, the shell finds the full path of the script and can execute it. However if you run the command from /maldini, as sh/run_program, then when the call to functiona is reached, the shell again looks for the script in the $PATH. However, the '.' now refers to /maldini (as it is the pwd). So the shell cannot find the path to the functiona script and fails.

The solution to the problem is to use the full path of any of your own shell scripts that you may call in a script.

By default "." i.e current directory is in your path and you are able to access the functiona when it lies in same directory.

To make sure the function a is always call irrespective of location introduce a line in your shell script


. $YOU_PATH/functiona
Here onwards your call to functiona will always be successful irrespective of your present location.


Regards,
Rishi

thanks for both of ur reply.
i solve the problem by cd to the working directory in my schedule job.
the reason why i never consider to use full path is because it will restrict my program flexibility or rather i need to change the path each time i need to use it in other place as well.