Monitor a file with tail with timestamps added

tail -f file | while read line; do echo -n $(date -u -Ins); echo -e "\t$line"; done

This is useful when watching a log file that does not contain timestamps itself. If the file already has content when starting the command, the first lines will have the "wrong" timestamp when the command was started and not when the lines were originally written.

By: hfs

2010-11-19 10:01:57

date echo file read tail tail date

3 Alternatives + Submit Alt

Monitor a file with tail with timestamps added
This is sample output - yours may be different.
9

tail -f file | awk '{now=strftime("%F %T%z\t");sub(/^/, now);print}'

arcege · 2010-11-25 04:11:52 7
Monitor a file with tail with timestamps added

Should be a bit more portable since echo -e/n and date's -Ins are not. Show Sample Output
This is sample output - yours may be different.
```
....
2010-11-24 05:46:58+0000        ##########
2010-11-24 05:46:59+0000        #  EOF   #
2010-11-24 05:46:59+0000        ##########
```
4

tail -f file | while read line; do printf "$(date -u '+%F %T%z')\t$line\n"; done

derekschrock · 2010-11-24 05:50:12 5
Monitor a file with tail with timestamps added
This is sample output - yours may be different.
3

tail -f file |xargs -IX printf "$(date -u)\t%s\n" X

unefunge · 2010-11-25 11:23:13 6

What Others Think

Where did you find -I switch? I don't see it in man date ...

depesz · 757 weeks and 1 day ago

Mmh, I don't remember. It's not listed in my man page, either. It seems to be the short form of '--rfc-3339='.

hfs · 757 weeks ago

Could be written with a single echo and without the 'line' variable tail -f file | while read; do echo -e "$(date -u -Ins)\t$REPLY"; done

frans · 756 weeks and 5 days ago

-I is for ISO8601 http://en.wikipedia.org/wiki/ISO_8601 But I don't know what the ns TIMESPEC would be..

derekschrock · 756 weeks and 3 days ago

Monitor a file with tail with timestamps added. If you don't want these time stamps for only to get monitor file for only where we have to want essay shark. Bring these changes ever when you see the file on the monitor that was the time we need to understand it.

Peodcqaxv · 262 weeks and 4 days ago

rahimhh21 · 142 weeks and 5 days ago

Perfecthomepugs · 133 weeks and 5 days ago

pugpuppies95 · 95 weeks and 6 days ago

yeneba6574 · 50 weeks and 4 days ago

What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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