Is there a command/program for OS X that allows me to hook to a file and display its changes in realtime without re-opening it, much like "top" monitors system processes in realtime?
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You can use tail to monitor single log file.
If file is deleted, then created again you may want to use tail -F to actively monitor file changes
If same file is being appended too use tail -f to actively monitor file changes
Hrvoje Špoljar
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gelraen
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1It doesn't seem to display changes as the file updates – Mark Feb 06 '11 at 18:38
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It does, at least on FreeBSD and linuxes. Should work on Mac OS X too. – gelraen Feb 06 '11 at 18:41
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@Mark how do you modify the file during checking? – ulidtko Feb 06 '11 at 18:48
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Perhaps it has something to do with the fact that the file is in a Dropbox and is updated perhaps a bit differently? – Mark Feb 06 '11 at 18:48
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It does work on OS X. On my systems anyway. – Sven Feb 06 '11 at 18:50
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2Try `tail -F`. Consult with `man tail` for more details about these options. – gelraen Feb 06 '11 at 18:51
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It also works on a Dropbox folder. – Sven Feb 06 '11 at 18:53
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-F instead of -f did it, thank you! – Mark Feb 06 '11 at 18:55
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`multitail` can monitor multiple files. – Dennis Williamson Feb 06 '11 at 19:51
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If you are doing this on file sync'd by dropbox the chances are it is creating a new file with a different inode so the tail -f command and the less +F command do not work since they are still referencing the old file handle they opened initially.
I suggest trying
watch "tail /path/to/filename"
It feels hackish but at least every X seconds it will re run tail on the filename giving you the updated output regardless of whether or not the inodes change on the file.
ScottZ
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