tail(1) — Commands
OSF
NAME
tail − Writes a file to standard output, beginning at a specified point
SYNOPSIS
tail [+|−number[unit]] [−r]
tail [+|−number[unit]] [−f file]
The tail command writes the named file (standard input by default) to standard output, beginning at a point you specify.
FLAGS
-fDoes not end after it copies the last line of the input file if the input file is not read from a pipe, but enters an endless loop in which it sleeps for a second and then attempts to read and copy further records from the input file. Thus, it can be used to monitor the growth of a file being written by another process. Has no effect if specified with -r.
-rCauses tail to print lines from the end of the file in reverse order. The default for -r is to print the entire file this way. Overrides -f.
−[number]l
−[number]b
−[number]k
−[number]c
−[number]m
Begins reading number lines (l), 512-byte blocks (b), 1-kilobyte blocks (k), characters (c and m) from the end of the input. m counts multi-byte characters as single-byte characters, while c counts characters byte-by-byte but does not break multi-byte characters. l for lines is the default unit. The default number is 10 for all units.
+[number]l
+[number]b
+[number]k
+[number]c
+[number]m
Begins reading number lines (l), 512-byte blocks (b), 1-kilobyte blocks (k), or characters (c and m) from the beginning of the input. m counts multi-byte characters as single-byte characters, while c counts characters byte-by-byte but does not break multi-byte characters. l for lines is the default unit. The default number is 10 for all units.
DESCRIPTION
If you do not specify -f, -r, -number, or +number, tail begins reading 10 lines before the end of the file. - (end of input) is the default starting point, l (lines) is the default unit, and 10 is the default number.
By specifying +, you can direct tail to read from the beginning of the file. By specifying a number or a unit, or both, you can change the point at which tail begins reading.
The unit argument can specify lines, blocks, or characters. The tail command can begin reading number (10 by default) units from either the end or the beginning of the file.
The block size is either 512 bytes or 1 kilobyte.
Japanese Language Support
When Japanese Language Support is enabled, tail -numberc begins reading as closely as possible to the number of bytes requested, without breaking a multi-byte character. The number of characters in input containing SJIS characters may not equal the number of bytes. You can use the -numberm flag to count multi-byte characters as single-byte characters.
EXAMPLES
1.To display the last 10 lines of a file named notes, enter:
tail notes
2.To specify how far from the end to start, enter:
tail -20 notes
This displays the last 20 lines of notes.
3.To specify how far from the beginning to start, enter:
tail +200c notes ⏐ more
This displays notes a page at a time, starting with the 200th character from the beginning.
4.To follow the growth of a file named accounts, enter:
tail -1 -f accounts
This displays the last line of accounts. Once every second, tail displays any lines that have been added to the file. This continues until stopped by pressing the Interrupt key sequence.