PRINTF(P) POSIX Programmer's Manual PRINTF(P)
printf - write formatted output
The printf utility shall write formatted operands to the standard output. The argument operands shall be formatted under control of the
The following operands shall be supported:
format A string describing the format to use to write the remaining operands. See the EXTENDED DESCRIPTION section.
The strings to be written to standard output, under the control of format. See the EXTENDED DESCRIPTION section.
The following environment variables shall affect the execution of printf:
LANG Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume of
IEEE Std 1003.1-2001, Section 8.2, Internationalization Variables for the precedence of internationalization variables used to
determine the values of locale categories.)
LC_ALL If set to a non-empty string value, override the values of all the other internationalization variables.
Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to
multi-byte characters in arguments).
Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error.
Determine the locale for numeric formatting. It shall affect the format of numbers written using the e , E , f , g , and G conver-
sion specifier characters (if supported).
Determine the location of message catalogs for the processing of LC_MESSAGES .
See the EXTENDED DESCRIPTION section.
The standard error shall be used only for diagnostic messages.
The format operand shall be used as the format string described in the Base Definitions volume of IEEE Std 1003.1-2001, Chapter 5, File
Format Notation with the following exceptions:
1. A <space> in the format string, in any context other than a flag of a conversion specification, shall be treated as an ordinary charac-
ter that is copied to the output.
2. A ' ' character in the format string shall be treated as a ' ' character, not as a <space>.
3. In addition to the escape sequences shown in the Base Definitions volume of IEEE Std 1003.1-2001, Chapter 5, File Format Notation (
'\' , 'a' , '' , 'f' , '
' , '
' , ' ' , 'v' ), "ddd" , where ddd is a one, two, or three-digit octal number, shall be writ-
ten as a byte with the numeric value specified by the octal number.
4. The implementation shall not precede or follow output from the d or u conversion specifiers with <blank>s not specified by the format
5. The implementation shall not precede output from the o conversion specifier with zeros not specified by the format operand.
6. The e , E , f , g , and G conversion specifiers need not be supported.
7. An additional conversion specifier character, b , shall be supported as follows. The argument shall be taken to be a string that may
contain backslash-escape sequences. The following backslash-escape sequences shall be supported:
* The escape sequences listed in the Base Definitions volume of IEEE Std 1003.1-2001, Chapter 5, File Format Notation ( '\' , 'a' ,
'' , 'f' , '
' , '
' , ' ' , 'v' ), which shall be converted to the characters they represent