Bash script runs manually, but fails on crontab - bash

Question

I'm a newbie to shell scripting. I have written a shell script to do incremental backup of MySQL database.The script is in executable format and runs successfully when executed manually but fails when executed through crontab.
Crontab entry is like this :
*/1 * * * * /home/db-backup/mysqlbackup.sh
Below is the shell script code -
#!/bin/sh
MyUSER="root" # USERNAME
MyPASS="password" # PASSWORD
MyHOST="localhost" # Hostname
Password="" #Linux Password
MYSQL="$(which mysql)"
if [ -z "$MYSQL" ]; then
echo "Error: MYSQL not found"
exit 1
fi
MYSQLADMIN="$(which mysqladmin)"
if [ -z "$MYSQLADMIN" ]; then
echo "Error: MYSQLADMIN not found"
exit 1
fi
CHOWN="$(which chown)"
if [ -z "$CHOWN" ]; then
echo "Error: CHOWN not found"
exit 1
fi
CHMOD="$(which chmod)"
if [ -z "$CHMOD" ]; then
echo "Error: CHMOD not found"
exit 1
fi
GZIP="$(which gzip)"
if [ -z "$GZIP" ]; then
echo "Error: GZIP not found"
exit 1
fi
CP="$(which cp)"
if [ -z "$CP" ]; then
echo "Error: CP not found"
exit 1
fi
MV="$(which mv)"
if [ -z "$MV" ]; then
echo "Error: MV not found"
exit 1
fi
RM="$(which rm)"
if [ -z "$RM" ]; then
echo "Error: RM not found"
exit 1
fi
RSYNC="$(which rsync)"
if [ -z "$RSYNC" ]; then
echo "Error: RSYNC not found"
exit 1
fi
MYSQLBINLOG="$(which mysqlbinlog)"
if [ -z "$MYSQLBINLOG" ]; then
echo "Error: MYSQLBINLOG not found"
exit 1
fi
# Get data in dd-mm-yyyy format
NOW="$(date +"%d-%m-%Y-%T")"
DEST="/home/db-backup"
mkdir $DEST/Increment_backup.$NOW
LATEST=$DEST/Increment_backup.$NOW
$MYSQLADMIN -u$MyUSER -p$MyPASS flush-logs
newestlog=`ls -d /usr/local/mysql/data/mysql-bin.?????? | sed 's/^.*\.//' | sort -g | tail -n 1`
echo $newestlog
for file in `ls /usr/local/mysql/data/mysql-bin.??????`
do
if [ "/usr/local/mysql/data/mysql-bin.$newestlog" != "$file" ]; then
echo $file
$CP "$file" $LATEST
fi
done
for file1 in `ls $LATEST/mysql-bin.??????`
do
$MYSQLBINLOG $file1>$file1.$NOW.sql
$GZIP -9 "$file1.$NOW.sql"
$RM "$file1"
done
$RSYNC -avz $LATEST /home/rsync-back
First of all, when scheduled on crontab it is not showing any errors. How can I get to know whether the script is running or not?
Secondly, what is the correct way to execute the shell script in a crontab.
Some blogs suggest for change in environment variables. What would be the best solution
When I did $echo PATH, I got this
/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/mysql/bin:/opt/android-sdk-linux/tools:/opt/android-sdk-linux/platform-tools:~/usr/lib/jvm/jdk-6/bin

Answer 1

The problem is probably that your $PATH is different in the manual environment from that under which crontab runs. Hence, which can't find your executables. To fix this, first print your path in the manual environment (echo $PATH), and then manually set up PATH at the top of the script you run in crontab. Or just refer to the programs by their full path.
Edit: Add this near the top of your script, before all the which calls:
export PATH="/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/mysql/bin:/opt/android-sdk-linux/tools:/opt/android-sdk-linux/platform-tools:~/usr/lib/jvm/jdk-6/bin"

Answer 2

Another more generic way is to have cron run the user's bash logon process. In addition to the PATH, this will also pick up any LD_LIBRARY_PATH, LANG settings, other environment variables, etc. To do this, code your crontab entry like:
34 12 * * * bash -l /home/db-backup/mysqlbackup.sh

Answer 3

My Issue was that I set the cron job in /etc/cron.d (Centos 7). It seems that when doing so I need to specify the user who executes the script, unlike when a cronjob is entered at a user level.
All I had to do was
*/1 * * * * root perl /path/to/my/script.sh
*/5 * * * * root php /path/to/my/script.php
Where "root" states that I am running the script as root.
Also need to make sure the following are defined at the top of the file. Your paths might be different. If you are not sure try the command "which perl", "which php".
SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin

Answer 4

Just import your user profile in the beginning of the script.
i.e.:
. /home/user/.profile

Answer 5

In your crontab file your script entry can have
* * * * * /bin/bash /path/to/your/script
Make sure to use full paths in your script. I have had a look through it and I have not seen any but just in case I missed it.

Answer 6

first run command env > env.tmp then run cat env.tmp copy PATH=.................. Full line and paste into crontab -e, line before your cronjobs. as like below
++=============================================================++
(# Edit this file to introduce tasks to be run by cron.
#
# Each task to run has to be defined through a single line
# indicating with different fields when the task will be run
# and what command to run for the task
#
# To define the time you can provide concrete values for
# minute (m), hour (h), day of month (dom), month (mon),
# and day of week (dow) or use '*' in these fields (for 'any').
#
# Notice that tasks will be started based on the cron's system
# daemon's notion of time and timezones.
#
# Output of the crontab jobs (including errors) is sent through
# email to the user the crontab file belongs to (unless redirected).
#
# For example, you can run a backup of all your user accounts
# at 5 a.m every week with:
# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
#
# For more information see the manual pages of crontab(5) and cron(8)
PATH=/root/.nvm/versions/node/v18.12.1/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/sna>
# m h dom mon dow command
0 3 * * * bash /home/ubuntu/test.sh
* * * * * bash /home/ubuntu/test2.sh >> /home/ubuntu/cronlog.log
* 3 * * * bash /home/ubuntu/logscron.sh)
++=====================================================================++