Cron job executing shell script sending empty email

Question

I wrote a shell script to automatically check the status of Oracle Data Guard and send it via mail.

If I execute the script manually it works like it should.

If I execute the script via a cronjob it just sends empty emails. This behaviour started only after we updated our servers from oracle linux 7 to oracle linux 8.

This is the script:

#!/bin/bash

#. ~/envBIPROD.sh
source /home/oracle/.bash_profile
source /home/oracle/envBIPROD.sh

dgmgrl -silent  user/pass >biprod.txt << EOF
show configuration;
show database p1biprod;
show database s1biprod;
EOF

cat biprod.txt | mail -r $(whoami).$(hostname -s)@hostname.tld -s "DATA GUARD Status biprod" [email protected]

This is the "envBIPROD.sh" script which sets the oracle home:

export ORACLE_SID=BIPROD1
export ORAENV_ASK=NO
. oraenv
export PATH=$ORACLE_HOME/bin:$ORACLE_HOME/OPatch:$PATH

Also the file "biprod.txt" is just empty when the script is run by cron.

Answer 1

Your script is probably running in a directory where it doesn't have permission to create or write to a file and so >biprod.txt is failing to create the file or to overwrite an existing file.

If biprod.txt is intended to only exist while your script is running then do this instead:

biprod=$(mktemp) || exit 1
trap 'rm -f "$biprod"; exit' EXIT

dgmgrl -silent  user/pass > "$biprod" 
...

cat "$biprod" | ...

though you almost certainly could be using < "$biprod" mail ... instead of cat "$biprod" | mail ...). It wouldn't hurt for you to add some printfs to report failures either.