printf(1) User Commands printf(1)
NAME
printf - write formatted output
SYNOPSIS
/usr/bin/printf
printf format [argument]...
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printf format [string...]
DESCRIPTION
/usr/bin/printf
The printf command writes formatted operands to the standard output. The argument operands are formatted under control of the format oper-
and.
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printf writes each string operand to standard output using format to control the output format.
OPERANDS
/usr/bin/printf
The following operands are supported by /usr/bin/printf:
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 can con-
tain 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 spec-
ification is reached. If the precision is omitted, it is taken to be infinite, so all bytes up to the end of the converted
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 operand 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 stan-
dard, 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 speci-
fication, a diagnostic message is written to standard error and the utility does not exit with a zero exit status, but contin-
ues processing any remaining operands and writes the value accumulated at the time the error was detected to standard output.
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The format operands support the full range of ANSI C formatting specifiers as well as additional specifiers.
The following additional specifiers are supported.
%b Processes each character in the string operand specially, as follows:
a Alert character.
Backspace character.
c Terminate output without appending NEWLINE. The remaining string operands are ignored.
E Escape character (ASCII octal 033).
f FORM FEED character.
NEWLINE character.
TAB character.
v Vertical tab character.
\ Backslash character.
x The 8-bit character whose ASCII code is the 1-, 2-, or 3-digit octal number x.
%B Treat the argument as a variable name and output the value without converting it to a string. This is most useful for variables of
type -b.
%H Output string with characters <, &, >, ", and non-printable characters, properly escaped for use in HTML and XML documents.
%P Treat string as an extended regular expression and convert it to a shell pattern.
%q Output string quoted in a manner that it can be read in by the shell to get back the same string. However, empty strings resulting
from missing string operands are not quoted.
%R Treat string as an shell pattern expression and convert it to an extended regular expression.
%T Treat string as a date/time string and format it. The T can be preceded by (dformat), where dformat is a date format as defined by
the date(1) command.
%Z Output a byte whose value is 0.
When performing conversions of string to satisfy a numeric format specifier, if the first character of string is "or', the value is the
numeric value in the underlying code set of the character following the "or'. Otherwise, string is treated like a shell arithmetic expres-
sion and evaluated.
If a string operand cannot be completely converted into a value appropriate for that format specifier, an error occurs, but remaining
string operands continue to be processed.
In addition to the format specifier extensions, the following extensions of ANSI-C are permitted in format specifiers:
o The escape sequences E and e expand to the escape character which is octal 033 in ASCII.
o The escape sequence cx expands to CTRL-x.
o The escape sequence C[.name.] expands to the collating element name.
o The escape sequence x{hex}expands to the character corresponding to the hexadecimal value hex.
o The format modifier flag = can be used to center a field to a specified width. When the output is a terminal, the character
width is used rather than the number of bytes.
o Each of the integral format specifiers can have a third modifier after width and precision that specifies the base of the con-
version from 2 to 64. In this case, the # modifier causes base# to be prepended to the value.
o The # modifier can be used with the d specifier when no base is specified to cause the output to be written in units of 1000
with a suffix of one of k M G T P E.
o The # modifier can be used with the i specifier to cause the output to be written in units of 1024 with a suffix of one of Ki Mi
Gi Ti Pi Ei.
If there are more string operands than format specifiers, the format string is reprocessed from the beginning. If there are fewer string
operands than format specifiers, then string specifiers are treated as if empty strings were supplied, numeric conversions are treated as
if 0 was supplied, and time conversions are treated as if now was supplied.
printf is equivalent to print -f, which allows additional options to be specified.
USAGE
/usr/bin/printf
The 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
/usr/bin/printf
Example 1 Printing a Series of Prompts
The following example alerts the user, then prints and reads 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
The following example prints a table of calculations. It reads out a list of right and wrong answers from a file, calculates the percentage
correctly, and prints 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
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 con-
version specification.
Example 4 Tabulating Conversion Errors
The following example tabulates conversion errors.
The printf utility tells the user when conversion errors are detected while producing numeric output. These 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 |
+-----------------------------------------------------------------------+
The value shown on standard output is what would be expected as the return value from the function strtol(3C). A similar correspondence
exists between %u and strtoul(3C), and %e, %f and %g and strtod(3C).
Example 5 Printing Output for a Specific Locale
The following example prints 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 |
+-----------------------------------------------------------+
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 representa-
tion 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:
/usr/bin/printf
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWloc |
+-----------------------------+-----------------------------+
|CSI |Enabled |
+-----------------------------+-----------------------------+
|Interface Stability |Committed |
+-----------------------------+-----------------------------+
|Standard |See standards(5). |
+-----------------------------+-----------------------------+
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+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWcsu |
+-----------------------------+-----------------------------+
|Interface Stability |Uncommitted |
+-----------------------------+-----------------------------+
SEE ALSO
awk(1), bc(1), date(1), echo(1), ksh93(1), printf(3C), strtod(3C), strtol(3C), strtoul(3C), attributes(5), environ(5), formats(5), stan-
dards(5)
SunOS 5.11 1 Nov 2007 printf(1)