Exit script if a file doesn't exist

Question

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

user1934428 · Accepted Answer · 2017-10-25 08:03:57Z

1

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.

answered Oct 25, 2017 at 8:03

user1934428

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Shachar Shemesh · Accepted Answer · 2017-10-25 07:43:51Z

1

You can check fr the existence of a file using:

if [ ! -f '/var/log/ngnix/error.log' ]
then
  exit
fi

answered Oct 25, 2017 at 7:43

Shachar Shemesh

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Comments

donaldgavis · Accepted Answer · 2017-10-25 23:34:36Z

1

Just check if file doesn't exist or is empty and exit code

LOG_FILE="/var/log/nginx/error.log" [ ! -s $LOG_FILE -o ! -f $LOG_FILE ] && exit $?

answered Oct 25, 2017 at 23:34

donaldgavis

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