|TAIL(1)||General Commands Manual||TAIL(1)|
tailutility displays the contents of file or, by default, its standard input, to the standard output. The display begins at a byte, line, or 512-byte block location in the input. Numbers having a leading plus (‘
+’) sign are relative to the beginning of the input, for example,
-c +2starts the display at the second byte of the input. Numbers having a leading minus (‘
-’) sign or no explicit sign are relative to the end of the input, for example,
-n 2displays the last two lines of the input. The default starting location is
-n 10, or the last 10 lines of the input. The options are as follows:
tailwill reopen the file and continue. If the file is truncated,
tailwill reset its position to the beginning. This makes
tailmore useful for watching log files that may get rotated. The
-foption is ignored if there are no file arguments and the standard input is a pipe or a FIFO.
-roption causes the input to be displayed in reverse order, by line. Additionally, this option changes the meaning of the
-noptions. When the
-roption is specified, these options specify the number of bytes, lines or 512-byte blocks to display, instead of the bytes, lines, or blocks from the beginning or end of the input from which to begin the display. The default for the
-roption is to display all of the input.
tailprecedes the output of each file with the following, in order to distinguish files:
==> file <==
tailutility exits 0 on success, and >0 if an error occurs.
$ tail -500 foo
$ tail -f /var/log/messages
tailutility is compliant with the IEEE Std 1003.1-2008 (“POSIX.1”) specification. The flags [
tailis supported by this implementation. The only difference between this implementation and historic versions of
tail, once the command line syntax translation has been done, is that the
-noptions modify the
-r -c 4displays the last 4 characters of the last line of the input, while the historic tail (using the historic syntax
-4cr) would ignore the
-coption and display the last 4 lines of the input.
tailcommand appeared in Version 7 AT&T UNIX.
|October 25, 2015||OpenBSD-current|