NAME
head —
extract file header
SYNOPSIS
head |
[-zqv] [-n
[-]lines|-c
[-]bytes]
[file]… |
DESCRIPTION
Copies the first lines (default 10) or bytes of each file (standard input stream if "-", the default) to the standard output stream.
With more than one file, each one is delineated by an empty line and
==>file<==
If lines or
bytes start with a -, all
but the last
lines or bytes of the
files are copied.
lines and bytes are in the mostly-case-insensitive format:
[base][b|KMGTPEZY[B]]
(with at least one of {base, b,
KMGTPEZY, B})
Where base is an optionally-floating-point number of
bytes, defaulting to 1, which is then optionally multiplied
by the relevant unit. B sets the unit multiplier to
1000 (from
1024).
b(lock) is a unit of
512.
lines|bytes is equal to
, if any, or base.
OPTIONS
-n,--lines=- Copy the first lines of each file. Default: 10.
-c,--bytes=- Copy the first bytes of each file.
-n,--lines=-lines- Copy all but the last lines of each file.
-c,--bytes=-bytes- Copy all but the last bytes of each file.
-z,--zero-terminated- Line separator is NUL, not newline. File headers are still written with newlines.
-q,--quiet,--silent- Never write file headers.
-v,--verbose- Always write file headers.
EXIT STATUS
1 if a file couldn't be opened or read.
EXAMPLES
$findtests/-type f -executable -exechead-n2{} +==> tests/head <== #!/bin/sh # SPDX-License-Identifier: 0BSD ==> tests/env/test <== #!/bin/sh # SPDX-License-Identifier: 0BSD ==> tests/env/code/env.1-3c <== #!/usr/bin/env -S PYTHONUNBUFFERED=1 python3 -S echo "PYTHONUNBUFFERED=$PYTHONUNBUFFERED" # Strip signature generated by Linux sign-file$head-c-754/lib/modules/$(uname-r)/updates/dkms/zfs.ko
SEE ALSO
tail(1) — ‘-’-marked
lines and bytes are symmetric,
and ‘+’-marked ones are almost
symmetric:
{head-c-10 f;tail-c-10 f;}{head-n+10 f;tail-n+11 f;}
cat f.
STANDARDS
Conforms to