tail -f fill not retry and load the new inode, tail -F will detect this. The same effect will happen if you rename/move a file. If you for example follows /var/log/messages and logrotate rotates the log to /var/log/messages.1. tail with -f will still listen to the old inode that points to messages.1. tail with -F will realize this and read the ...

From the tail(1) man page: With --follow (-f), tail defaults to following the file descriptor, which means that even if a tail’ed file is renamed, tail will continue to track its end. This default behavior is not desirable when you really want to track the actual name of the file, not the file descrip- tor (e.g., log rotation).

Nov 28, 2013 · Barring your files don't include strange characters in their names, such as spaces, new lines, etc. A simple pipe to tail -n 200 should suffice. Example. Sample data. $ touch $(seq 300) Now the last 200: $ ls -l | tail -n 200 You might not like the …

grep "2014-01-01 21:" log.txt; tail -f log.txt It will print everything from that hour, and keep tailing. or you can also use awk to print everything from start of an certain hour to end of file, and keep tailing after it, this will allow you to tail last few hours if needed. awk '/2014-01-01 21:/' log.txt; tail …

You can pipe the tail -f into sed, telling it to quit when it sees the line you're searching for: tail -f /path/to/file.log | sed '/^Finished: SUCCESS$/ q' sed will output each line it processes by default, and exit after it sees that line. The tail process will stop when it tries to write the next line and sees its output pipe is broken

In addition, tail will not read any more than head, so thus we have shown that head | tail reads the fewest number of lines possible (again, plus some negligible buffering that we are ignoring). The only efficiency advantage of a single tool approach that does not use pipes is fewer processes (and thus less overhead).

From the tail man page (GNU tail, that is):-n, --lines=K output the last K lines, instead of the last 10; or use -n +K to output lines starting with the Kth Thus, the following should append all but the first 2 lines of somefile.txt to anotherfile.txt: tail --lines=+3 somefile.txt >> anotherfile.txt

Use --follow=name in that case. That causes tail to track the named file in a way that accommodates renaming, removal and creation. So, the tail portion of my command equates to tail --follow --retry --lines=+0, where the final argument directs it …

Note that this spawns a new tail process every second, which might or might not be something you care about. Also, be sure to specify a sub-second interval (e.g. watch -n 0.1) to simulate the "constantly updating" part. (This obviously increases the …

Then, read from it. You can always do that with things like tail, to minimize output, etc. Whenever you clear the pipe (read from it), it gets cleared, so the output is not preserved. The other option would be to write everything to a file (much like a logfile) and then analyze it an any time.