PRINTF (UNIX)

printf
Developer(s)	Various open-source and commercial developers
Operating system	Unix and Unix-like
Platform	Cross-platform
Type	Command
License	coreutils: GPLv3+

In Unix and Unix-like operating systems, printf is a shell builtin (and utility program^[2]) that formats and outputs text like the same-named C function.

Originally named for outputting to a printer, it actually outputs to standard output.^[3]

The command accepts a format string, which specifies how to format values, and a list of values.

Characters in the format string are copied to the output verbatim except when a format specifier is found which causes a value to be output.

In addition to the standard format specifiers, %b causes the command to expand backslash escape sequences (for example \n for newline), and %q outputs an item that can be used as shell input.^[3] The format string is reused if there are more items than format specs. Unused format specs provide a zero value or null string.

History

printf is part of the X/Open Portability Guide since issue 4 of 1992. It was inherited into the first version of POSIX.1 and the Single Unix Specification.^[4] It first appeared in 4.3BSD-Reno.^[5]

The version of printf bundled in GNU coreutils was written by David MacKenzie. It has an extension %q for escaping strings in POSIX-shell format.^[3]

Examples

$ for NUMBER in  4 6 8 9 10
> do printf " >> %03d %d<< \n" $NUMBER $RANDOM
> done
 >> 004 26305<<
 >> 006 6687<<
 >> 008 20170<<
 >> 009 28322<<
 >> 010 4400<<

This will print a directory listing, emulating 'ls':

$ printf "%s\n" *

References

^ "printf(1): format/print data - Linux man page". linux.die.net.
^ "GNU Coreutils". www.gnu.org.
^ ^a ^b ^c printf(1) – Linux User Manual – User Commands
^ printf – Shell and Utilities Reference, The Single UNIX Specification, Version 4 from The Open Group
^ printf(1) – FreeBSD General Commands Manual

External links

[coreutils-1] "printf(1): format/print data - Linux man page". linux.die.net.

[2] "GNU Coreutils". www.gnu.org.

[:0-3] printf(1) – Linux User Manual – User Commands

[4] printf – Shell and Utilities Reference, The Single UNIX Specification, Version 4 from The Open Group

[5] printf(1) – FreeBSD General Commands Manual

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v t e Unix command-line interface programs and shell builtins
File system	cat chattr chmod chown chgrp cksum cmp cp dd du df file fuser ln ls mkdir mv pax pwd rm rmdir split tee touch type umask
Processes	at bg crontab fg kill nice ps time
User environment	env exit logname mesg talk tput uname who write
Text processing	awk basename comm csplit cut diff dirname ed ex fold head iconv join m4 more nl paste patch printf read sed sort strings tail tr troff uniq vi wc xargs
Shell builtins	alias cd echo test unset wait
Searching	find grep
Documentation	man
Software development	ar ctags lex make nm strip yacc
Miscellaneous	bc cal expr lp od sleep true and false
Categories Standard Unix programs Unix SUS2008 utilities List

v t e Unix command-line interface programs and shell builtins
File system	cat chattr chmod chown chgrp cksum cmp cp dd du df file fuser ln ls mkdir mv pax pwd rm rmdir split tee touch type umask
Processes	at bg crontab fg kill nice ps time
User environment	env exit logname mesg talk tput uname who write
Text processing	awk basename comm csplit cut diff dirname ed ex fold head iconv join m4 more nl paste patch printf read sed sort strings tail tr troff uniq vi wc xargs
Shell builtins	alias cd echo test unset wait
Searching	find grep
Documentation	man
Software development	ar ctags lex make nm strip yacc
Miscellaneous	bc cal expr lp od sleep true and false
Categories Standard Unix programs Unix SUS2008 utilities List

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References

External links

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Developer(s)	Various open-source and commercial developers
Operating system	Unix and Unix-like
Platform	Cross-platform
Type	Command
License	coreutils: GPLv3+^[1]