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linuxshelldatetimeunixutc

Exit script if a file doesn't exist

I try to calculate time differences between two log, but when there is no log in logfile, unix takes own birthdate 1970. My script is below. I want to exit from script if there is no log in logfile.

#!/bin/bash
a=`tail -n 1 /var/log/nginx/error.log | awk -F" " '{print $1" "$2}' | cut -c12-20`
f=`date '+%Y-%m-%d %H:%M:%S' | cut -c12-19`
VAR1=$(date -u --date="$a sec UTC" +%s)
VAR2=$(date -u --date="$f sec UTC" +%s)
DIFF2=$(( $VAR2 - $VAR1 ))
if [ $DIFF2 -lt 59 ]; then
echo "ok"
else
echo "nok"
fi
Solution

  • I guess that with if there is no log in logfile, you mean that the logfile either does not exist or is empty. You can do this in bash with

    logfile=/var/log/nginx/error.log
[[ -f $logfile && -s $logfile ]] || exit 1

    -f tests that it is a plain file, and -s tests that it is not empty.