tail1
Display the last part of a file
Usage
tail [{-f | -r}]
[{-b
number | -c
number | -n
number | -number}]
[file ...]
Overview
The tail utility 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 +2 starts 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 2 displays 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:
-
-b number -
The location is number 512-byte blocks.
-
-c number -
The location is number bytes.
-
-f -
Do not stop when end-of-file is reached; instead, wait for additional data to be appended to the input. If the file is replaced (i.e., the inode number changes),
tailwill reopen the file and continue. If the file is truncated,tailwill reset its position to the beginning. This makestailmore 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. -nnumber |-number-
The location is number lines.
-
-r -
The
-roption causes the input to be displayed in reverse order, by line. Additionally, this option changes the meaning of the-b,-c, and-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.
If more than one file is specified, tail precedes the output of each file with the following, in order to distinguish files:
==> file <==
Exit status
The tail utility exits 0 on success, and >0 if an error occurs.
Examples
To display the last 500 lines of the file foo:
$ tail -500 foo
Keep /var/log/messages open, displaying to the standard output anything appended to the file:
$ tail -f /var/log/messages
Releases
61 releases since OpenBSD 2.1; the text changed 15 times.
-n until OpenBSD 5.6;
-number until OpenBSD 5.6.