Linux in a Nutshell, Fifth Edition

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Bash and Korn

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printf

printf format [val ...]

Not ksh88. Formatted printing, like the ANSI C printf function.

Additional Format Letters

Both Bash and ksh93 accept additional format letters. Bash

provides only %b and %q, while ksh93 provides all those in the

following list:

%b Expand escape sequences in strings (e.g., \t to tab, and so on).

%B The corresponding argument is a variable name (typically

created via typeset -b); its value is retrieved and printed.

%d An additional period and the output base can follow the preci-

sion (e.g., %5.3.6d to produce output in base 6).

%H Output strings in HTML/XML format. (Spaces become

&nbsp; and < and > become &lt; and &gt;.)

%n Place the number of characters printed so far into the named

variable.

%P Translate egrep extended regular expression into ksh pattern.

%q Print a quoted string that can be reread later on.

%R Reverse of %P: translate ksh pattern into egrep extended

regular expression.

%(format)T

Print a string representing a date and time according to the

strftime(3) format format. The parentheses are entered liter-

ally. See the Examples.

%Z Print an ASCII NUL (8 zero bits).

Examples

$ date Reformat date/time

Tue Sep 7 15:39:42 EDT 2004

$ printf "%(It is now %m/%d/%Y %H:%M:%S)T\n" "$(date)"

It is now 09/07/2004 15:40:10

$ printf "%H\n" "Here ...