76 lines
2.2 KiB
Groff
76 lines
2.2 KiB
Groff
.TH TAIL 1
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.SH NAME
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tail \- output the last part of files
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.SH SYNOPSIS
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.B tail
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[\-c [+]N[bkm]] [\-n [+]N] [\-fqv] [\-\-bytes=[+]N[bkm]] [\-\-lines=[+]N]
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[\-\-follow] [\-\-quiet] [\-\-silent] [\-\-verbose] [file...]
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.B tail
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[{\-,+}Nbcfklmqv] [file...]
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.SH DESCRIPTION
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This manual page
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documents the GNU version of
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.BR tail .
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.B tail
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prints the last part (10 lines by default) of each given file; it
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reads from standard input if no files are given or when a filename of
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`\-' is encountered. If more than one file is given, it prints a
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header consisting of the file's name enclosed in `==>' and `<=='
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before the output for each file.
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.PP
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The GNU
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.B tail
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can output any amount of data, unlike the Unix version, which uses a
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fixed size buffer. It has no
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.I \-r
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option (print in reverse). Reversing a file is really a different job
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from printing the end of a file; the BSD
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.B tail
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can only reverse files that are at most as large as its buffer, which
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is typically 32k. A reliable and more versatile way to reverse files is
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the GNU
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.B tac
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command.
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.SS OPTIONS
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.PP
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.B tail
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accepts two option formats: the new one, in which numbers are
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arguments to the option letters, and the old one, in which a `+' or
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`\-' and optional number precede any option letters.
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.PP
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If a number (`N') starts with a `+',
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.B tail
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begins printing with the Nth item from the start of each file, instead
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of from the end.
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.TP
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.I "\-c N, \-\-bytes N"
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Tail by N bytes. N is a nonzero integer, optionally followed by one
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of the following characters to specify a different unit.
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.RS
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.IP b
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512-byte blocks.
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.IP k
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1-kilobyte blocks.
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.IP m
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1-megabyte blocks.
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.RE
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.TP
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.I "\-f, \-\-follow"
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Loop forever trying to read more characters at the end of the file, on
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the assumption that the file is growing. Ignored if reading from a
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pipe. Cannot be used if more than one file is given.
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.TP
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.I "\-l, \-n N, \-\-lines N"
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Tail by N lines.
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.TP
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.I "\-q, \-\-quiet, \-\-silent"
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Never print filename headers.
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.TP
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.I "\-v, \-\-verbose"
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Always print filename headers.
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.PP
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The long-named options can be introduced with `+' as well as `\-\-',
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for compatibility with previous releases. Eventually support for `+'
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will be removed, because it is incompatible with the POSIX.2 standard.
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