printf(1) User Commands printf(1)NAMEprintf - write formatted output
SYNOPSISprintf 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:
· A SPACE character in the format string, in any
context other than a flag of a conversion specifi‐
cation, is treated as an ordinary character that
is copied to the output.
· A character in the format string is treated as a
character, not as a SPACE character.
· 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 num‐
ber.
· The program does not precede or follow output from
the d or u conversion specifications with blank
characters not specified by the format operand.
· The program does not precede output from the o
conversion specification with zeros not specified
by the format operand.
· An additional conversion character, b, is sup‐
ported as follows. The argument is taken to be a
string that may contain backslash-escape
sequences. The following backslash-escape
sequences are supported:
· the escape sequences listed on the for‐
mats(5) manual page (\\, \a, \b, \f, \n, \r,
\t, \v), which are converted to the charac‐
ters they represent
· \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
· \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 preci‐
sion is omitted, it is taken to be infinite, so all
bytes up to the end of the converted string are writ‐
ten. 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 neces‐
sary 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 standard, with the following
extensions:
· A leading plus or minus sign is allowed.
· 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 writ‐
ten 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 preci‐
sion 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 conver‐
sion specification, the printf utility reports an error. Thus, overflow
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 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 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 ALSOawk(1), bc(1), echo(1), printf(3C), strtod(3C), strtol(3C), str‐
toul(3C), attributes(5), environ(5), formats(5), standards(5)SunOS 5.10 28 Mar 1995 printf(1)
