<code>printf</code> is a shell command that formats and outputs text like the same-named C function. It is available in a variety of Unix and Unix-like systems. Some shells implement the command as builtin and some provide it as a utility program
The command has similar syntax and semantics as the library function. The command outputs text to standard output as specified by a format string and a list of values. Characters of the format string are copied to the output verbatim except when a format specifier is found which causes a value to be output per the specifier.
The command has some aspects unlike the library function. In addition to the library function format specifiers, <code>%b</code> causes the command to expand backslash escape sequences (for example <code>\n</code> for newline), and <code>%q</code> outputs an item that can be used as shell input. The value used for an unmatched specifier (too few values) is an empty string for or 0 for a numeric specifier. If there are more values than specifiers, then the command restarts processing the format string from its beginning,
The command 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. It first appeared in 4.3BSD-Reno.
The implementation bundled in GNU Core Utilities was written by David MacKenzie. It has an extension for escaping strings in POSIX-shell format.
This prints a list of numbers:
This produces output for a directory's content similar to <code>ls</code>: