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TAIL(1) General Commands Manual TAIL(1) NAME tail -- display the last part of a file SYNOPSIS tail [-F | -f | -r] [-qv] [-b number | -c number | -n number] [file ...] DESCRIPTION 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, --blocks=number The location is number 512-byte blocks. -c number, --bytes=number The location is number bytes. -f The -f option causes tail to not stop when end of file is reached, but rather to wait for additional data to be appended to the input. The -f option is ignored if the standard input is a pipe, but not if it is a FIFO. -F The -F option implies the -f option, but tail will also check to see if the file being followed has been renamed or rotated. The file is closed and reopened when tail detects that the filename be- ing read from has a new inode number. If the file being followed does not (yet) exist or if it is re- moved, tail will keep looking and will display the file from the beginning if and when it is created. The -F option is the same as the -f option if reading from standard input rather than a file. -n number, --lines=number The location is number lines. -q, --quiet, --silent Suppresses printing of headers when multiple files are being exam- ined. -r The -r option causes the input to be displayed in reverse order, by line. Additionally, this option changes the meaning of the -b, -c and -n options. When the -r option 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 -r option is to display all of the input. -v, --verbose Prepend each file with a header. If more than a single file is specified, or if the -v option is used, each file is preceded by a header consisting of the string "==> XXX <==" where XXX is the name of the file. The -q flag disables the printing of the header in all cases. All number arguments may also be specified with size suffixes supported by expand_number(3). EXIT STATUS The tail utility exits 0 on success, and >0 if an error occurs. EXAMPLES Display the last 500 lines of the file foo: $ tail -n 500 foo Keep /var/log/messages open, displaying to the standard output anything ap- pended to the file: $ tail -F /var/log/messages Read /var/log/messages from the beginning and then follow the file as usual: $ tail -F -n +1 /var/log/messages SEE ALSO cat(1), head(1), sed(1), expand_number(3) STANDARDS The tail utility is expected to be a superset of the IEEE Std 1003.2-1992 ("POSIX.2") specification. In particular, the -F, -b and -r options are extensions to that standard. The historic command line syntax of tail is supported by this implementa- tion. The only difference between this implementation and historic ver- sions of tail, once the command line syntax translation has been done, is that the -b, -c and -n options modify the -r option, i.e., "-r -c 4" dis- plays the last 4 characters of the last line of the input, while the his- toric tail (using the historic syntax "-4cr") would ignore the -c option and display the last 4 lines of the input. HISTORY A tail command appeared in PWB UNIX. FreeBSD ports 15.quarterly November 28, 2023 TAIL(1)
NAME | SYNOPSIS | DESCRIPTION | EXIT STATUS | EXAMPLES | SEE ALSO | STANDARDS | HISTORY
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