printf(1) User Commands printf(1)
NAME
printf - write formatted output
SYNOPSIS
printf format [argument...]
DESCRIPTION
The printf command writes formatted operands to the standard output. The argument operands are formatted under control of the format oper-
and.
OPERANDS
The following operands are supported:
format A string describing the format to use to write the remaining operands. The format operand is used as the format string
described on the formats(5) manual page, with the following exceptions:
o A SPACE character in the format string, in any context other than a flag of a conversion specification, is treated as
an ordinary character that is copied to the output.
o A character in the format string is treated as a character, not as a SPACE character.
o In addition to the escape sequences described on the formats(5) manual page (\, a, , f,
,
, , v), ddd,
where ddd is a one-, two- or three-digit octal number, is written as a byte with the numeric value specified by the
octal number.
o The program does not precede or follow output from the d or u conversion specifications with blank characters not
specified by the format operand.
o The program does not precede output from the o conversion specification with zeros not specified by the format oper-
and.
o An additional conversion character, b, is supported as follows. The argument is taken to be a string that may contain
backslash-escape sequences. The following backslash-escape sequences are supported:
o the escape sequences listed on the formats(5) manual page (\, a, , f,
,
, , v), which are converted
to the characters they represent
o ddd, where ddd is a zero-, one-, two- or three-digit octal number that is converted to a byte with the numeric
value specified by the octal number
o c, which is written and causes printf to ignore any remaining characters in the string operand containing it,
any remaining string operands and any additional characters in the format operand.
The interpretation of a backslash followed by any other sequence of characters is unspecified.
Bytes from the converted string are written until the end of the string or the number of bytes indicated by the precision
specification is reached. If the precision is omitted, it is taken to be infinite, so all bytes up to the end of the con-
verted string are written. For each specification that consumes an argument, the next argument operand is evaluated and
converted to the appropriate type for the conversion as specified below. The format operand is reused as often as necessary
to satisfy the argument operands. Any extra c or s conversion specifications are evaluated as if a null string argument
were supplied; other extra conversion specifications are evaluated as if a zero argument were supplied. If the format oper-
and contains no conversion specifications and argument operands are present, the results are unspecified. If a character
sequence in the format operand begins with a % character, but does not form a valid conversion specification, the behavior
is unspecified.
argument The strings to be written to standard output, under the control of format. The argument operands are treated as strings if
the corresponding conversion character is b, c or s. Otherwise, it is evaluated as a C constant, as described by the ISO C
standard, with the following extensions:
o A leading plus or minus sign is allowed.
o If the leading character is a single- or double-quote, the value is the numeric value in the underlying codeset of the
character following the single- or double-quote.
If an argument operand cannot be completely converted into an internal value appropriate to the corresponding conversion
specification, a diagnostic message is written to standard error and the utility does not exit with a zero exit status, but
continues processing any remaining operands and writes the value accumulated at the time the error was detected to standard
output.
USAGE
Notice that this printf utility, like the printf(3C) function on which it is based, makes no special provision for dealing with multi-byte
characters when using the %c conversion specification or when a precision is specified in a %b or %s conversion specification. Applications
should be extremely cautious using either of these features when there are multi-byte characters in the character set.
Field widths and precisions cannot be specified as *.
For compatibility with previous versions of SunOS 5.x, the $ format specifier is supported for formats containing only %s specifiers.
The %b conversion specification is not part of the ISO C standard; it has been added here as a portable way to process backslash escapes
expanded in string operands as provided by the echo utility. See also the USAGE section of the echo(1) manual page for ways to use printf
as a replacement for all of the traditional versions of the echo utility.
If an argument cannot be parsed correctly for the corresponding conversion specification, the printf utility reports an error. Thus, over-
flow and extraneous characters at the end of an argument being used for a numeric conversion are to be reported as errors.
It is not considered an error if an argument operand is not completely used for a c or s conversion or if a string operand's first or sec-
ond character is used to get the numeric value of a character.
EXAMPLES
Example 1: Printing a series of prompts
To alert the user and then print and read a series of prompts:
example% printf "aPlease fill in the following:
Name: "
read name
printf "Phone number: "
read phone
Example 2: Printing a table of calculations
To read out a list of right and wrong answers from a file, calculate the percentage correctly, and print them out. The numbers are right-
justified and separated by a single tab character. The percentage is written to one decimal place of accuracy:
example% while read right wrong ; do
percent=$(echo "scale=1;($right*100)/($right+$wrong)" | bc)
printf "%2d right %2d wrong (%s%%)
"
$right $wrong $percent
done < database_file
Example 3: Printing number strings
The command:
example% printf "%5d%4d
" 1 21 321 4321 54321
produces:
1 21
3214321
54321 0
Notice that the format operand is used three times to print all of the given strings and that a 0 was supplied by printf to satisfy the
last %4d conversion specification.
Example 4: Tabulating conversion errors
The printf utility tells the user when conversion errors are detected while producing numeric output; thus, the following results would be
expected on an implementation with 32-bit twos-complement integers when %d is specified as the format operand:
+-------------------------------------------------------------------+
| Arguments Standard Diagnostic |
|5a 5 printf: 5a not completely converted |
|9999999999 2147483647 printf: 9999999999: Results too |
| large |
|-9999999999 -2147483648 printf: -9999999999: Results too |
| large |
|ABC 0 printf: ABC expected numeric value |
+-------------------------------------------------------------------+
Notice that the value shown on standard output is what would be expected as the return value from the function strtol(3C). A similar corre-
spondence exists between %u and strtoul(3C), and %e, %f and %g and strtod(3C).
Example 5: Printing output for a specific locale
In a locale using the ISO/IEC 646:1991 standard as the underlying codeset, the command:
example% printf "%d
" 3 +3 -3 '3 "+3 "'-3"
produces:
+-----------------------------------------------------------+
|3 Numeric value of constant 3 |
|3 Numeric value of constant 3 |
|-3 Numeric value of constant -3 |
|51 Numeric value of the character `3' in the ISO/IEC |
| 646:1991 standard codeset |
|43 Numeric value of the character `+' in the ISO/IEC |
| 646:1991 standard codeset |
|45 Numeric value of the character `-' in the SO/IEC |
| 646:1991 standard codeset |
+-----------------------------------------------------------+
Notice that in a locale with multi-byte characters, the value of a character is intended to be the value of the equivalent of the wchar_t
representation of the character.
If an argument operand cannot be completely converted into an internal value appropriate to the corresponding conversion specification, a
diagnostic message is written to standard error and the utility does exit with a zero exit status, but continues processing any remaining
operands and writes the value accumulated at the time the error was detected to standard output.
ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment variables that affect the execution of printf: LANG, LC_ALL, LC_CTYPE, LC_MES-
SAGES, LC_NUMERIC, and NLSPATH.
EXIT STATUS
The following exit values are returned:
0 Successful completion.
>0 An error occurred.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWloc |
+-----------------------------+-----------------------------+
|CSI |enabled |
+-----------------------------+-----------------------------+
|Interface Stability |Standard |
+-----------------------------+-----------------------------+
SEE ALSO
awk(1), bc(1), echo(1), printf(3C), strtod(3C), strtol(3C), strtoul(3C), attributes(5), environ(5), formats(5), standards(5)
SunOS 5.10 28 Mar 1995 printf(1)