Format and print data.
Write the formatted arguments to the standard output under the control
of the format.
Syntax
printf format [arguments ...]
The format is a character string which contains three types of objects:
The arguments after the first are treated as strings if the corresponding format is either c, b or s otherwise it is evaluated as a C constant, 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 ASCII code of the next character.
The format string is reused as often as necessary to satisfy the arguments. Any extra format specifications are evaluated with zero or the null string.
Character escape sequences are in backslash notation as defined in the ANSI X3.159-1989 (`ANSI C89'), with extensions. The characters and their meanings are as follows:
\a Write a bell character. \b Write a backspace character. \c Ignore remaining characters in this string. \f Write a form-feed character. \n Write a new-line character. \r Write a carriage return character. \t Write a tab character. \v Write a vertical tab character. \' Write a single quote character. \\ Write a backslash character. \num \0num Write an 8-bit character whose ASCII value is the 1-, 2-, or 3-digit octal number num.
Each format specification is introduced by the percent character (`%'). The remainder of the format specification includes, in the following order:
Zero or more of the following flags:
# A `#' character specifying that the value should be printed in an `alternate form'.
For c, d, and s, formats, this option has no effect. For the o formats the precision
of the number is increased to force the first character of the output string to a zero.
For the x (X) format, a non-zero result has the string 0x (0X) prepended to it. For e,
E, f, g, and G, formats, the result will always contain a decimal point, even if no
digits follow the point (normally, a decimal point only appears in the results of those
formats if a digit follows the decimal point). For g and G formats, trailing zeros are
not removed from the result as they would otherwise be;
- A minus sign specifies left adjustment of the output in the indicated field;
+ Always place a sign before the number when using signed formats.
' ' A space specifying that a blank should be left before a positive number for a signed
format. A '+' overrides a space if both are used;
0 Use zero-padding rather than blank-padding. A - overrides a 0 if both are used.
Field Width:
An optional digit string specifying a field width; if the output string has fewer characters
than the field width it will be blank-padded on the left (or right, if the left-adjustment
indicator has been given) to make up the field width (note that a leading zero is a flag, but
an embedded zero is part of a field width);
Precision:
An optional period, `.', followed by an optional digit string giving a precision which specifies
fies the number of digits to appear after the decimal point, for e and f formats, or the maximum
number of characters to be printed from a string; if the digit string is missing, the precision
is treated as zero;
Format:
A character which indicates the type of format to use (one of diouxXfFeEgGaAcsb). The uppercase
formats differ from their lowercase counterparts only in that the output of the former is
entirely in uppercase. The floating-point format specifiers (fFeEgGaA) can be prefixed by an L
to request that additional precision be used, if available.
A field width or precision can be '*' instead of a digit string. In this case an argument supplies the
field width or precision.
The format characters and their meanings are:
diouXx The argument is printed as a signed decimal (d or i), unsigned octal, unsigned decimal, or
unsigned hexadecimal (X or x), respectively.
fF The argument is printed in the style `[-]ddd.ddd' where the number of d’s after the decimal
point is equal to the precision specification for the argument. If the precision is missing,
, 6 digits are given; if the precision is explicitly 0, no digits and no decimal point
are printed. The values infinity and NaN are printed as `inf' and `nan', respectively.
eE The argument is printed in the style e `[-d.ddd+-dd]' where there is one digit before the
decimal point and the number after is equal to the precision specification for the argument
when the precision is missing, 6 digits are produced. The values infinity and NaN
are printed as `inf' and `nan', respectively.
gG The argument is printed in style f (F) or in style e (E) whichever gives full precision in
minimum space.
aA The argument is printed in style `[-h.hhh+-pd]' where there is one digit before the hexadecimal
point and the number after is equal to the precision specification for the argument;
when the precision is missing, enough digits are produced to convey the argument’s
exact double-precision floating-point representation. The values infinity and NaN are
printed as `inf' and `nan', respectively.
c The first character of argument is printed.
s Characters from the string argument are printed until the end is reached or until the number
of characters indicated by the precision specification is reached; however if the precision
is 0 or missing, all characters in the string are printed.
b As for s, but interpret character escapes in backslash notation in the string argument.
% Print a `%'; no argument is used.
The decimal point character is defined in the program’s locale (category LC_NUMERIC).
In no case does a non-existent or small field width cause truncation of a field; padding takes place only if the specified field width exceeds the actual width.
Since the floating point numbers are translated from ASCII to floating- point and then back again, floating-point precision can be lost. (By default, the number is translated to an IEEE-754 double-pre-cision double-precision
cision value before being printed. The L modifier might produce additional precision, depending on the
hardware platform.)
ANSI hexadecimal character constants were deliberately not provided.
The escape sequence \000 is the string terminator. When present in the argument for the b format, the argument will be truncated at the \000 character.
Multibyte characters are not recognized in format strings (this is only a problem if `%' can appear inside a multibyte character).
Exits 0 on success, 1 on failure.
printf is a bash builtin command.
Print the decimal number 5 followed by a newline (\n):
printf "%d\n" 5
# 5
Print as float (default 6 decimal places):
printf "%f\n" 5
# 5.000000
Print text followed by variable $USER:
printf "Hello, $USER.\n\n"
Print multiple lines:
printf %s "\
with quotes we can echo
several lines at a time
"
Display variables:
distance=15
printf "Distance is %5d Miles\n" $distance
# Distance is 15 Miles
Echo a list of numbers from 1 to 100, adding 3 digits of Zero padding so they appear as 001, 002, 003 etc:
for ((num=1;num<=100;num+=1)); do echo `printf "%03d" $num`; done
Use \n anywhere to start a new line:
printf "Two separate\nlines\n"
# Two separate
# lines
Print decimal numbers interspersed with text:
printf "There are %d orders valued at over %d euros.\n" 64 1500
# There are 64 orders valued at over 1500 euros.
Print text interspersed with command results:
printf "This is `uname -s` running on a `uname -m` processor.\n\n"
Convert a hex number to decimal:
$ printf "%d\n " 0xF
15
Convert a decimal number to Hex:
printf "0x%X\n " 15
# 0xF
Convert a decimal number to Octal:
printf "0%o\n " 8
# 010
Convert an Octal number to decimal:
printf "%d\n " 010
# 8
“Fortune favours the bold, Fortune favours the brave” ~ Latin proverb
echo - Display message on screen.
lpr - Print files.