Alvin Bakker Alvin Bakker - 1 year ago 104
Bash Question

Shell script for making database backups works only from prompt

I have a shell script that works fine from the command prompt, but from my cron job it throws

unexpected operator

NOW=$(date +"%Y%m%d-%H%M")
MYSQL="$(which mysql)"
MYSQLDUMP="$(which mysqldump)"
GZIP="$(which gzip)"

find $BACKUP/* -mtime +15 -exec rm {} \;

DBS="$($MYSQL -h $MHOST -u $MUSER -p$MPASS -Bse 'show databases')"
for db in $DBS

if [ "$db" == "myDBase" ]; then
if [ "$db" != "performance_schema" ]; then
echo $db

I am accessing the script using crontab
20 0 * * * var/www/backups/

The errors I get are:

/var/www/backups/ 20: [: information_schema: unexpected operator
/var/www/backups/ 20: [: mysql: unexpected operator
/var/www/backups/ 20: [: olb: unexpected operator
/var/www/backups/ 20: [: performance_schema: unexpected operator

I am running the latest version of mySQL on Ubuntu 14.04. Doe anyone have an idea why?

Answer Source

Without specifying your shell, you will get /bin/sh by default (tested on Ubuntu 14.04). The [ built-in for sh does not support the == operator, so sh doesn't know how to compare $db and myDBase on line 20.

You should always start your scripts with a "#!" line to specify a shell. To get bash, the first line would be #!/bin/bash.

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