Shell – Calling scripts from inside other scripts

cronshell-script

I have a script which I call every 10 minutes with a cronjob:

*/10 * * * * ~/mydirectory/myscript.sh

Now, inside ~/mydirectory there is also another script, let's say myotherscript.sh which I'd like to call from inside myscript.sh. Both scripts have been chmod'ed to be executable and when I execute myscript.sh from the command line inside ~/mydirectory everything works fine. I execute it as follows:

. myscript.sh

But it doesn't look like the cronjob works. When I remove the reference to the second script from inside the primary script, it works though so I suspect there is something wrong with the way I reference the second script. This is what the contents of myscript.sh looks like:

#! /bin/bash
do-something
do-something-else
. myotherscript.sh

Could it be that, when the cronjob runs, the current directory is not ~/mydirectory and so the cronjob can't find the myotherscript.sh file? If so, how to I get it to see the file? I don't want to specify the absolute path inside the primary script as I might want to move it (and myotherscript.sh) to another directory at some point or I might want to rename ~/mydirectory at some point and I don't then want to have to change the contents of myscript.sh to reference the new absolute path.

BONUS QUESTION: Right now, when it's time for the cronjob to execute I basically just hold thumbs and hope for the best but I have no way of seeing whether it was successful and if it failed, why it failed. Any tips on how I can see why the cronjob didn't execute as expected?

Best Answer

OK, so glenn jackman's answer works and it also answered my bonus question but I have since figured out another and what I believe to be more elegant way of making sure the cronjob runs in the directory in which the scripts are located.

Simply by replacing

*/10 * * * * ~/mydirectory/myscript.sh

with

*/10 * * * * cd ~/mydirectory && ./myscript.sh

And that solves the problem. Everything works.

Related Solutions

Bash – Obtain script current directory (so that I can do include files without relative paths and run the script from everywhere)

The $0 variable contains the script's path:

$ cat ~/bin/foo.sh
#!/bin/sh
echo $0

$ ./bin/foo.sh
./bin/foo.sh

$ foo.sh
/home/terdon/bin/foo.sh

$ cd ~/bin
$ foo.sh
./foo.sh

As you can see, the output depends on the way it was called, but it always returns the path to the script relative to the way the script was executed. You can, therefore, do:

## Set mydir to the directory containing the script
## The ${var%pattern} format will remove the shortest match of
## pattern from the end of the string. Here, it will remove the
## script's name,. leaving only the directory. 
mydir="${0%/*}"

# config load
source "$mydir"/config.sh

If the directory is in your $PATH, things are even simpler. You can just run source config.sh. By default, source will look for files in directories in $PATH and will source the first one it finds:

$ help source
source: source filename [arguments]
    Execute commands from a file in the current shell.

Read and execute commands from FILENAME in the current shell.  The
entries in $PATH are used to find the directory containing FILENAME.
If any ARGUMENTS are supplied, they become the positional parameters
when FILENAME is executed.

If you are sure your config.sh is unique or, at least, that it is the first one found in $PATH, you can source it directly. However, I suggest you don't do this and stick to the first method instead. You never know when another config.sh might be in your $PATH.

Bash Scripts – Using Absolute Path in Bash Scripts

You have it exactly right - the environment of cron may have a PATH that does not include /usr/local/bin/. You can fix this by, in your script, appending that directory to the PATH:

PATH="$PATH:/usr/local/bin/"

The best practice, though, is indeed to use explicit paths for all external binaries that a script calls just in case (for instance) a maliciously designed program conveniently called cp gets dropped into the PATH somewhere before /bin.

Best Answer

Related Solutions

Bash – Obtain script current directory (so that I can do include files without relative paths and run the script from everywhere)

Bash Scripts – Using Absolute Path in Bash Scripts

Related Question