printf (Unix)
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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] |
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" *
See also
- printf, the C function
References
- ^ "printf(1): format/print data - Linux man page". linux.die.net.
- ^ "GNU Coreutils". www.gnu.org.
- ^ a b c – Linux User Manual – User Commands
- ^ – Shell and Utilities Reference, The Single UNIX Specification, Version 4 from The Open Group
- ^ – FreeBSD General Commands Manual
External links
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