printf — stdin stdout - file -- opt --help --version
printf command is an
echo: it prints
formatted strings on standard output. It operates much like the C
programming language function
), which applies a format string to a sequence of
arguments to create some specified output. For example:
$ printf "User %s is %d years old.\n" sandy 29 User sandy is 29 years old.
The first argument is the format string, which in our example
contains two format specifications,
%d. The subsequent arguments, sandy and
29, are substituted by
into the format string and then printed. Format specifications can
get fancy with floating-point numbers:
$ printf "That\'ll be $%0.2f, sir.\n" 3 That'll be $3.00, sir.
There are two
commands available in Linux: one built into the bash shell, and one
in /usr/bin/printf. The two are
identical except for one format specification,
%q, supported only by the bash built-in:
it prints escape symbols (“
\”) so its output can
be used as shell input safely. Note the difference:
$ printf "This is a quote: %s\n" "\"" This is a quote: " $ printf "This is a quote: %q\n" "\"" This is a quote: \"
It is your responsibility to make sure the number of format
%) equals the
number of arguments supplied to
printf. If you have too many arguments,
the extras are ignored, and if you have too few,
printf assumes default values (0 for numeric formats, an empty string for string formats). Nevertheless, ...