head (Unix)
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This article needs additional citations for verification. (June 2020) |
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| head | |
|---|---|
| Lua error in package.lua at line 80: module 'Module:InfoboxImage/data' not found. Example usage of head command to display first 5 lines of Lorem ipsum in the specified file | |
| [[Programmer|DeveloperTemplate:Pluralize from text]] | Various open-source and commercial developers |
| Operating system | Unix, Unix-like, MSX-DOS, IBM i |
| Platform | Cross-platform |
| Type | Command |
| License | coreutils: GPLv3 |
| Website | Script error: No such module "WikidataIB". |
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head is a program on Unix and Unix-like operating systems used to display the beginning of a text file or piped data.
Syntax
The command syntax is:
head [options] ⟨file_name⟩
By default, Template:Tt will print the first 10 lines of its input to the standard output.
Option flags
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- Template:Tt ⟨count⟩
- Template:Tt=⟨count⟩
- The number of lines printed may be changed with a command line option. The following example shows the first 20 lines of filename:
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head -n 20 filename
This displays the first 5 lines of all files starting with foo:
Page Template:Pre/styles.css has no content.head -n 5 foo*
Most versions[citation needed] allow omittingnand instead directly specifying the number:-5. GNU head allows negative arguments for the-noption, meaning to print all but the last - argument value counted - lines of each input file. - Template:Tt ⟨bytes⟩
- Template:Tt=⟨bytes⟩
- Print first x number of bytes.
Other command
Many early versions of Unix and Plan 9 did not have this command, and documentation and books used sed instead:
sed 5q filename
The example prints every line (implicit) and quit after the fifth.
Equivalently, awk may be used to print the first five lines in a file:
awk 'NR < 6' filename
However, neither sed nor awk were available in early versions of BSD, which were based on Version 6 Unix, and included head.[1]
Implementations
A head command is also part of ASCII's MSX-DOS2 Tools for MSX-DOS version 2.[2] The Page Template:Mono/styles.css has no content.head command has also been ported to the IBM i operating system.[3]
See also
References
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- ^ Page Module:Citation/CS1/styles.css has no content.Spinellis, Diomidis (2022). "dspinellis/unix-history-man: Version 1.0 web pages (v1.1-web)". Zenodo. doi:10.5281/zenodo.7248228.
- ^ MSX-DOS2 Tools User's Manual by ASCII Corporation
- ^ Page Module:Citation/CS1/styles.css has no content.IBM. "IBM System i Version 7.2 Programming Qshell" (PDF). Archived (PDF) from the original on 2020-09-18. Retrieved 2020-09-05.
External links
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- head manual page from GNU coreutils.
- FreeBSD documentation for head
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