"command not found" when running a script via cron

To avoid having to type the absolute path to a command, shells introduced the $PATH environment variable, each directory is separated by a : and searches are done from left to right. cron often clears the whole environment, including this $PATH variable. Therefore, the script may behave differently in your cron compared to the behavior in the shell.

Use absolute paths

Run which db2 as db2inst1 user to get the full path for the db2 program. If the output is /usr/bin/db2, your cron command would look like:

/usr/bin/db2 connect to myDB2

Set the PATH variable

Run echo "$PATH" as db2inst1 user to get the $PATH variable and make sure this variable is available in your cron script too. For example, if the output was /usr/local/bin:/usr/bin:/bin, you would put the next line in the top of your shell script:

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

As answered in https://askubuntu.com/a/23438/227839, you should set PATH in your shell script:

#!/bin/bash
PATH="/usr/local/bin:/usr/bin:/bin"

# rest of script follows

or in the crontab file, which will apply to all cron jobs:

PATH="/usr/local/bin:/usr/bin:/bin"
0 1 * * * db2 connect to myDB2

You must define what db2 and myDB2 are, otherwise use the absolute location of 'file' or 'application' which want to run.

Example:

/bin/rm /home/ubuntu/a.txt