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 operand.
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 for-
mats(5) manual page, with the following excep-
tions:
o A SPACE character in the format string, in
any context other than a flag of a conver-
sion specification, is treated as an ordi-
nary character that is copied to the out-
put.
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, \b, \f, \n, \r, \t, \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 out-
put from the d or u conversion specifica-
tions 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 operand.
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, \b,
\f, \n, \r, \t, \v), which are con-
verted to the characters they
represent
o \0ddd, 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 char-
acters in the string operand contain-
ing 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
converted string are written. For each specifica-
tion 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 sup-
plied; other extra conversion specifications are
evaluated as if a zero argument were supplied. If
the format operand contains no conversion specif-
ications 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 specifica-
tion, 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 follow-
ing 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 con-
verted into an internal value appropriate to the
corresponding conversion specification, a diag-
nostic 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) func-
tion on which it is based, makes no special provision for
dealing with multi-byte characters when using the %c conver-
sion 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 pro-
cess backslash escapes expanded in string operands as pro-
vided 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, overflow and extraneous characters
at the end of an argument being used for a numeric conver-
sion 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 second 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: \nName: "
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\t%2d wrong\t(%s%%)\n" \
$right $wrong $percent
done < database_file
Example 3: Printing number strings
The command:
example% printf "%5d%4d\n" 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 correspondence 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\n" 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 conver-
sion specification, a diagnostic message is written to stan-
dard 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_MESSAGES, 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 attri-
butes:
____________________________________________________________
| 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), stan-
dards(5)
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