HEAD(1) User Commands HEAD(1)


NAME


head - display first few lines of files

SYNOPSIS


/usr/bin/head
/usr/bin/head [-q] [-v] [-number ] [ -n number ] [ -c number] [filename]...


ksh93
head [-qv] [-n lines] [-c chars] [-s skip] [filename]...


DESCRIPTION


/usr/bin/head
The head utility copies the first number of lines of each filename to the
standard output. If no filename is given, head copies lines from the
standard input. The default value of number is 10 lines. If -c is
specified, head copies the first number of bytes of each filename.


When more than one file is specified, the start of each file looks like:

==> filename <==


Thus, a common way to display a set of short files, identifying each one,
is:

example% head -9999 filename1 filename2 ...


ksh93
The head built-in in ksh93 is associated with the /bin and /usr/bin
paths. It is invoked when head is executed without a pathname prefix and
the pathname search finds a /bin/head or /usr/bin/head executable.


head copies one or more input files to standard output, stopping at a
designated point for each file or to the end of the file whichever comes
first. Copying ends at the point indicated by the options. By default, a
header of the form ==> filename <== is output before all but the first
file but this can be changed with the -q and -v options. If no file is
given, or if the file is -, head copies from standard input starting at
the current location.


The option argument for -c and -s can optionally be followed by one of
the following characters to specify a different unit other than a single
byte:

b
512 bytes


k
1-kilobyte


m
1-megabyte


For backwards compatibility, -number is equivalent to -n number.

OPTIONS


/usr/bin/head
The following options are supported by /usr/bin/head:

-n number
The first number lines of each input file is copied to
standard output. The number option-argument must be a
positive decimal integer.


-c number
The first number bytes of each input file is copied to
standard output. The number option-argument must be a
positive decimal integer. Note, output may end in the middle
of a character if a file contains multi-byte characters.


-number
The number argument is a positive decimal integer with the
same effect as the -n number option.


-q
head will not print a header in between each specified file.


-v
head will always print a header before each file, even if
only one file is specified.


If no options are specified, head acts as if -n 10 had been specified.

ksh93
The following options are supported by the head built-in command in
ksh93:

-n
--lines=lines
Copy lines from each file. The default value is 10.


-c
--bytes=chars
Copy chars bytes from each file.


-q
--quiet|silent
Never output filename headers.


-s
--skip=skip
Skip skip characters or lines from each file before
copying.


-v
--verbose
Always output filename headers.


OPERANDS


The following operand is supported:

filename
A path name of an input file. If no file operands are
specified, the standard input is used.


USAGE


See largefile(7) for the description of the behavior of head when
encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).

EXAMPLES


Example 1: Writing the First Ten Lines of All Files




The following example writes the first ten lines of all files, except
those with a leading period, in the directory:


example% head *


ENVIRONMENT VARIABLES


See environ(7) for descriptions of the following environment variables
that affect the execution of head: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES,
and NLSPATH.

EXIT STATUS


The following exit values are returned:

0
Successful completion.


>0
An error occurred.


ATTRIBUTES


See attributes(7) for descriptions of the following attributes:

/usr/bin/head

+--------------------+-------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-------------------+
|CSI | Enabled |
+--------------------+-------------------+
|Interface Stability | Committed |
+--------------------+-------------------+
|Standard | See standards(7). |
+--------------------+-------------------+

ksh93

+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | See below. |
+--------------------+-----------------+


The ksh93 built-in binding to /bin and /usr/bin is Volatile. The built-
in interfaces are Uncommitted.

SEE ALSO


cat(1), ksh93(1), more(1), pg(1), tail(1), attributes(7), environ(7),
largefile(7), standards(7)


September 12, 2020 HEAD(1)