printf(1) General Commands Manual printf(1)
NAME
printf - format and print arguments
SYNOPSIS
format [arg ...]
DESCRIPTION
writes formatted arguments to the standard output. The arg arguments are formatted under control of the format operand.
format is a character string patterned after the formatting conventions of (see printf(3S)), and contains the following types of objects:
characters Characters that are not escape sequences or conversion specifications (as described below) are copied to stan-
dard output.
escape sequences These are interpreted as non-graphic characters:
alert
backspace
form-feed
new-line
carriage return
tab
vertical tab
single quote character
backslash
the 8-bit character whose ASCII
code is the 1-, 2-, 3-, or 4-digit octal number n, whose first character must be a zero.
conversion specification
Specifies the output format of each argument (see below).
Arguments following format are interpreted as strings if the corresponding format is either or otherwise they are treated as con-
stants.
Conversion Specifications
Each conversion specification is introduced by the percent character After the character, the following can appear in the sequence indi-
cated:
flags Zero or more flags, in any order, which modify the meaning of the conversion specification. The flag characters and
their meanings are:
The result of the conversion is left-justified within the field.
The result of a signed conversion always begins with a sign,
or
<space> If the first character of a signed conversion is not a sign, a space character is prefixed to the result.
This means that if the space flag and flag both appear, the space flag is ignored.
The value is to be converted to an "alternate form". For
and conversions, this flag has no effect. For conversion, it increases the precision to force the first
digit of the result to be a zero. For or conversion, a non-zero result has or prefixed to it. For and
conversions, the result always contains a radix character, even if no digits follow the radix character.
For and conversions, trailing zeros are not removed from the result, contrary to usual behavior.
field width An optional string of decimal digits to specify a minimum field width. For an output field, if the converted value has
fewer bytes than the field width, it is padded on the left (or right, if the left-adjustment flag, has been given) to
the field width.
precision The precision specifies the minimum number of digits to appear for the or conversions (the field is padded with leading
zeros), the number of digits to appear after the radix character for the and conversions, the maximum number of signifi-
cant digits for the conversion, or the maximum number of bytes to be printed from a string in s conversion. The preci-
sion takes the form of a period followed by a decimal digit string. A null digit string is treated as a zero.
conversion characters
A conversion character indicates the type of conversion to be applied:
The integer argument is printed a signed decimal
or unsigned octal unsigned decimal or unsigned hexadecimal notation and The conversion uses the numbers and
letters and the conversion uses the numbers and letters The precision component of the argument specifies
the minimum number of digits to appear. If the value being converted can be represented in fewer digits
than the specified minimum, it is expanded with leading zeroes. The default precision is 1. The result of
converting a zero value with a precision of 0 is no characters.
The floating-point number argument
is printed in decimal notation in the style , where the number of digits after the radix character, is
equal to the precision specification. If the precision is omitted from the argument, six digits are out-
put; if the precision is explicitly 0, no radix appears.
The floating-point-number argument is printed in the style
, where there is one digit before the radix character, and the number of digits after it is equal to the
precision. When the precision is missing, six digits are produced; if the precision is 0, no radix charac-
ter appears. The conversion character produces a number with introducing the exponent instead of The expo-
nent always contains at least two digits. However, if the value to be printed requires an exponent greater
than two digits, additional exponent digits are printed as necessary.
The floating-point-number argument is printed in style
or (or int style in the case of a conversion character), with the precision specifying the number of sig-
nificant digits. The style used depends on the value converted; style is used only if the exponent result-
ing from the conversion is less than or greater than or equal to the precision. Trailing zeros are remove
from the result. A radix character appears only if it is followed by a digit.
The first byte of the argument is printed.
The argument is taken to be a string,
and characters from the string are printed until the end of the string or the number of bytes indicated by
the precision specification of the argument is reached. If the precision is omitted from the argument, it
is interpreted as infinite and all characters up to the end of the string are printed.
Print a character; no argument is converted.
Similar to the
conversion specifier, except that the string can contain backslash-escape sequences which are then con-
verted to the characters they represent. will cause to ignore any remaining characters in the string oper-
and containing it, any remaining string operands and any additional characters in the format operand.
In no case does a nonexistent or insufficient field width cause truncation of a field; if the result of a conversion is
wider than the field width, the field is simply expanded to contain the conversion result.
EXTERNAL INFLUENCES
Environment Variables
determines the interpretation of arg as single and/or multi-byte characters.
determines the language in which messages are displayed.
If or is not specified in the environment or is set to the empty string, the value of is used as a default for each unspecified or empty
variable. If is not specified or is set to the empty string, a default of "C" (see lang(5)) is used instead of
If any internationalization variable contains an invalid setting, printf behaves as if all internationalization variables are set to "C".
See environ(5).
International Code Set Support
Single and multi-byte character code sets are supported.
RETURN VALUE
exits with one of the following values:
Successful completion.
Errors occurred; the exit value is increased by one for each error that
occurred up to a maximum of 255.
DIAGNOSTICS
If an argument cannot be converted into a form suitable for the corresponding conversion specification, or for any other reason cannot be
correctly printed, a diagnostic message is printed to standard error, the argument is output as a string form as it was given on the com-
mand line, and the exit value is incremented.
EXAMPLES
The following command prints the number 123 in octal, hexadecimal and floating point formats in their alternate form
printf "%#o, %#x, %#X, %#f, %#g, %#e
" 123 123 123 123 123 123
resulting in the following output
Print the outputs with their corresponding field widths and precision:
printf "%.6d, %10.6d, %.6f, %.6e, %.6s
" 123 123 1.23 123.4 MoreThanSix
resulting in the following output
SEE ALSO
echo(1), printf(3S).
STANDARDS CONFORMANCE
printf(1)
