Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

and

Unix-like A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-li ...

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ef ...

s, printf ("print formatted") is a

shell builtin In computing, a shell builtin is a command or a function, called from a shell, that is executed directly in the shell itself, instead of an external executable program which the shell would load and execute. Shell builtins work significantly f ...

(and utility program) that formats and prints data. The

command Command may refer to: Computing * Command (computing), a statement in a computer language * COMMAND.COM, the default operating system shell and command-line interpreter for DOS * Command key, a modifier key on Apple Macintosh computer keyboards ...

accepts a

printf format string The printf format string is a control parameter used by a class of functions in the input/output libraries of C and many other programming languages. The string is written in a simple template language: characters are usually copied literal ...

, which specifies methods for formatting items, and a list of items to be formatted. Named historically after the intention of printing to a

printer Printer may refer to: Technology * Printer (publishing), a person or a company * Printer (computing), a hardware device * Optical printer for motion picture films People * Nariman Printer (fl. c. 1940), Indian journalist and activist * James ...

, it now actually outputs to

stdout In computer programming, standard streams are interconnected input and output communication channels between a computer program and its environment when it begins execution. The three input/output (I/O) connections are called standard input (stdin ...

Characters Character or Characters may refer to: Arts, entertainment, and media Literature * ''Character'' (novel), a 1936 Dutch novel by Ferdinand Bordewijk * ''Characters'' (Theophrastus), a classical Greek set of character sketches attributed to The ...

in the format string are copied to the output or, if a % is encountered, are used to format an item. In addition to the standard formats, %b causes printf to expand backslash

escape sequence In computer science, an escape sequence is a combination of characters that has a meaning other than the literal characters contained therein; it is marked by one or more preceding (and possibly terminating) characters. Examples * In C and ma ...

s (for example \n for

newline Newline (frequently called line ending, end of line (EOL), next line (NEL) or line break) is a control character or sequence of control characters in character encoding specifications such as ASCII, EBCDIC, Unicode, etc. This character, or a ...

), and %q outputs an item that can be used as

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology * Seashell, a hard o ...

input. The format string is reused if there are more items than format specs. Unused format specs provide a zero value or

null string In formal language theory, the empty string, or empty word, is the unique string of length zero. Formal theory Formally, a string is a finite, ordered sequence of characters such as letters, digits or spaces. The empty string is the special cas ...

History

is part of the

X/Open X/Open group (also known as the Open Group for Unix Systems and incorporated in 1987 as X/Open Company, Ltd.) was a consortium founded by several European UNIX systems manufacturers in 1984 to identify and promote open standards in the field of in ...

Portability Guide since issue 4 of 1992. It was inherited into the first version of POSIX.1 and the Single Unix Specification. It first appeared in

4.3BSD-Reno The History of the Berkeley Software Distribution begins in the 1970s. 1BSD (PDP-11) The earliest distributions of Unix from Bell Labs in the 1970s included the source code to the operating system, allowing researchers at universities to modify ...

. The version of printf bundled in

GNU GNU () is an extensive collection of free software Free software or libre software is computer software distributed under terms that allow users to run the software for any purpose as well as to study, change, and distribute it and any ...

coreutils The GNU Core Utilities or coreutils is a package of GNU software containing implementations for many of the basic tools, such as cat, ls, and rm, which are used on Unix-like operating systems. In September 2002, the ''GNU coreutils'' were c ...

was written by David MacKenzie. It has an extension for escaping strings in POSIX-shell format.

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

External links

{{Unix commands Standard Unix programs IBM i Qshell commands

History

Examples

See also

References

External links