Adding time stamp to log file in bash script

Question

My script is as follows

if ps ax | grep -v grep | grep ./program > /dev/null     then         exit     else         echo "---------------------------------------------------" >> Debug.log         echo "Starting program at:  $(date)" >> Debug.log         ./program >> Debug.log 2>&1 fi exit 

Via crontab, this script is run every minute. It checks to see if a certain program is running, if it is, great, if not, starts it up.

Now I would like to append timestamps every time the script runs into Debug.log if it found ./program to be running. So under the then line, I added:

echo "Time: $(date)" >> Debug.log 

This command does not output anything to Debug.log. It does work however directly from the command line. Why is that so, and can I remedy the problem?

Answer 1

Note you are outputting to Debug.log, while you should indicate the full path of that file: echo "Time: $(date)" >> /path/to/Debug.log.

---

In general, whenever you want to add timestamp to a log file, you can use:

echo "Time: $(date). Some error info." >> /path/to/your/file.log 

date will expand to something like Fri Sep 9 12:18:02 CEST 2016. In that case, you may prefer to use some date flags to have a more parseable date:

$ date "+%FT%T" 2016-09-09T12:18:23 

Or, even better, using the ISO 8601 format:

$ date -Iseconds 2016-09-09T12:18:23+0200 

All together:

echo "Time: $(date -Iseconds). Some error info." >> /path/to/your/file.log