Shell 脚本不会从 cron 作业执行

Question

shell script:

#!/bin/sh
services=( httpd named proftpd mysqld dovecot postfix webmin)

for service in ${services[@]}
do

if ps ax | grep -v grep | grep $service > /dev/null
then
    echo "$service service running, everything is fine"     
else
    echo "$service is not running"
    service $service start
fi

done 

file executable, running from root user

command:

bash /etc/mycron/checkServices.sh

tried sh and just /etc/mycron/checkServices.sh

doesn't run

Answer 1

#!/bin/sh
services=( httpd named proftpd mysqld dovecot postfix webmin)

for service in ${services[@]}; do
    if ps ax | grep -v grep | grep $service > /dev/null; then
        echo "$service service running, everything is fine";
    else
        echo "$service is not running";
        service $service start;
    fi;
done;

Works fine here... maybe you want to add after #!/bin/sh PATH="/bin:/sbin:/usr/bin:/usr/sbin:/opt/usr/bin:/opt/usr/sbin:/usr/local/bin:/usr/local/sbin"

You could also do chmod 775 /etc/mycron/checkServices.sh to make it executable, which is needed for cron. Then you would also not need to call bash /etc/mycron/checkServices.sh and can just call /etc/mycron/checkServices.sh the #!/bin/sh tells the executable loader to load the file with /bin/sh if you invoke bash /etc/mycron/checkServices.sh you will start bash which on his turn would start /bin/sh to finally execute your script.

Since the for loop in bash / sh uses the IFS variable ( $IFS ) as delimiter, you could also make the line services=(httpd named proftpd mysqld dovecot postfix webmin) as services="httpd named proftpd mysqld dovecot postfix webmin" since this is more general

Answer 2

Just as a general diagnostic process, it's sensible to insert trace statements into the script such as:

• echo "Starting..."
• echo "Checking for running service '$service'..."
• which/whereis service
• echo "Service has been started."
• temporarily remove the > /dev/null for ps .

Then execute under cron with stdout and stderr redirected to a log file.

That allows you to identify the exact line that's failing. As others have said, it looks likely to be the "service" or "$service" commands aren't found because the PATH isn't set to include them. You do realise "service" itself is being sought as an external command that presumably launched $service in turn? Also keep an eye on root's mail, as cron sometimes sends error reports via mail.