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 ...

You can think of -f as "follow". When -f is added to tail, the command will not exit but waits to see if more is added to the file; that additional text will be printed by tail. You normally kill a tail -f with ^c. It is often used with log files that that are being written by daemons or a background user process. tail -f /var/log/syslog

2021年5月3日 · Depending on your shell and your data, echo "$(tail -n1 file1),$(tail -n1 file3)" >>file2 may or may not work. It's guaranteed to work if the first column doesn't start with - and no column contains a backslash.

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).

2013年11月28日 · 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 way the results are presented in that list of 200.

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).

2014年1月30日 · Try out multitail¹.This is an übergeneralization of tail -f.You can watch multiple files in separate windows, highlight lines based on their content, and more.

@OlivierDulac, tail -n +1 (read anything from the start position) addresses the race condition concerns. It will read the lines that were not in the file at the time wc -l terminated, from the exact position wc left it. So NR will have the right position regardless of how many lines have been written in between wc ending and tail starting.

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 …