Loading ...Shell scripting: Write message to a syslog / log file
syslog is the protocol as well as application to send message to Linux system logfile located at /var/log directory.
Sysklogd provides two system utilities which provide support for system logging and kernel message trapping.
Usually most program and apps use C or syslog application / library sending syslog messages.
But how do you send message from a shell prompt or shell script?
logger command
Use logger command which is a shell command interface to the syslog system log module. It makes or writes one line entries in the system log file from the command line.
Log message System rebooted for hard disk upgrade
$ logger System rebooted for hard disk upgrade
You can see message in /var/log/message file
# tail -f /var/log/message
Output:
Jan 26 20:53:31 dell6400 logger: System rebooted for hard disk upgrade
You can use logger command from a shell script. Consider following example:
#!/bin/bash HDBS="db1 db2 db3 db4" BAK="/sout/email" [ ! -d $BAK ] && mkdir -p $BAK || : /bin/rm $BAK/* NOW=$(date +"%d-%m-%Y") ATTCH="/sout/backup.$NOW.tgz" [ -f $ATTCH ] && /bin/rm $ATTCH || : MTO="you@yourdomain.com" for db in $HDBS do FILE="$BAK/$db.$NOW-$(date +"%T").gz" mysqldump -u admin -p'password' $db | gzip -9 > $FILE done tar -jcvf $ATTCH $BAK mutt -s "DB $NOW" -a $ATTCH $MTO <<EOF DBS $(date) EOF [ "$?" != "0" ] && logger "$0 - MySQL Backup failed" || :
Last line will log a message in /var/log/message file if backup failed.
Other usage
To log a message contained in the /var/log/myapp.log file, use:
$ logger -f /var/log/myapp.log
Log the message to standard error (screen), as well as the system log:
$ logger -s "Hard disk full"
Refer to the man page for more options:
man logger
man syslogd
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If you want to log to a remote Syslog server, the logger command will not work as it logs only to the syslogd on the localhost. log4sh is a logging framework for shell scripts that *can* log to a remote Syslog server as long as netcat is installed.
the following code is not writing either of the messagesto /var/log/messages.What is wrong in the code?
My file is saved at /usr/local/sbin location.example is the name of my file.
if [ -e /usr/local/sbin/example ]; then
logger File exists
else
logger File does not exist
fi
I have added the above code in /etc/rc.local file.
Thankyou in advance