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printf(1) printf(1)
NAME
printf - format and print arguments
SYNOPSIS
format [arg ...]
DESCRIPTION
writes formatted arguments to the standard output. The arg arguments
are formatted under control of the format operand.
format is a character string patterned after the formatting conventions
of (see printf(3S)), and contains the following types of objects:
characters Characters that are not escape sequences or
conversion specifications (as described
below) are copied to standard output.
escape sequences These are interpreted as non-graphic charac‐
ters:
alert
backspace
form-feed
new-line
carriage return
tab
vertical tab
single quote character
backslash
the 8-bit character whose ASCII
code is the 1-, 2-, 3-, or
4-digit octal number n, whose
first character must be a zero.
conversion specification
Specifies the output format of each argument
(see below).
Arguments following format are interpreted as strings if the
corresponding format is either or otherwise they are treated as
constants.
Conversion Specifications
Each conversion specification is introduced by the percent character
After the character, the following can appear in the sequence indi‐
cated:
flags Zero or more flags, in any order, which modify the
meaning of the conversion specification. The flag
characters and their meanings are:
The result of the conversion is left-justified
within the field.
The result of a signed conversion always begins
with a sign,
or
<space> If the first character of a signed
conversion is not a sign, a space
character is prefixed to the result.
This means that if the space flag and
flag both appear, the space flag is
ignored.
The value is to be converted to an "alternate
form". For
and conversions, this flag has no
effect. For conversion, it increases
the precision to force the first
digit of the result to be a zero.
For or conversion, a non-zero result
has or prefixed to it. For and con‐
versions, the result always contains
a radix character, even if no digits
follow the radix character. For and
conversions, trailing zeros are not
removed from the result, contrary to
usual behavior.
field width An optional string of decimal digits to specify a
minimum field width. For an output field, if the
converted value has fewer bytes than the field
width, it is padded on the left (or right, if the
left-adjustment flag, has been given) to the field
width.
precision The precision specifies the minimum number of digits
to appear for the or conversions (the field is
padded with leading zeros), the number of digits to
appear after the radix character for the and conver‐
sions, the maximum number of significant digits for
the conversion, or the maximum number of bytes to be
printed from a string in s conversion. The preci‐
sion takes the form of a period followed by a deci‐
mal digit string. A null digit string is treated as
a zero.
conversion characters
A conversion character indicates the type of conver‐
sion to be applied:
The
inte‐
ger
argu‐
ment
is
printed
a
signed
dec‐
i‐
mal or
unsigned
octal
unsigned
dec‐
i‐
mal
or
unsigned
hexa‐
dec‐
i‐
mal
nota‐
tion
and
The
con‐
ver‐
sion
uses
the
num‐
bers
and
let‐
ters
and
the
con‐
ver‐
sion
uses
the
num‐
bers
and
let‐
ters
The
pre‐
ci‐
sion
com‐
po‐
nent
of
the
argu‐
ment
spec‐
i‐
fies
the
min‐
i‐
mum
num‐
ber
of
dig‐
its
to
appear.
If
the
value
being
con‐
verted
can
be
rep‐
re‐
sented
in
fewer
dig‐
its
than
the
spec‐
i‐
fied
min‐
i‐
mum,
it
is
expanded
with
lead‐
ing
zeroes.
The
default
pre‐
ci‐
sion
is
1.
The
result
of
con‐
vert‐
ing
a
zero
value
with
a
pre‐
ci‐
sion
of
0
is
no
char‐
ac‐
ters.
The
float‐
ing-
point
num‐
ber
argu‐
ment is
printed
in
dec‐
i‐
mal
nota‐
tion
in
the
style
,
where
the
num‐
ber
of
dig‐
its
after
the
radix
char‐
ac‐
ter,
is
equal
to
the
pre‐
ci‐
sion
spec‐
i‐
fi‐
ca‐
tion.
If
the
pre‐
ci‐
sion
is
omit‐
ted
from
the
argu‐
ment,
six
dig‐
its
are
out‐
put;
if
the
pre‐
ci‐
sion
is
explic‐
itly
0,
no
radix
appears.
The
float‐
ing-
point-
num‐
ber
argu‐
ment
is
printed
in
the
style ,
where
there
is
one
digit
before
the
radix
char‐
ac‐
ter,
and
the
num‐
ber
of
dig‐
its
after
it
is
equal
to
the
pre‐
ci‐
sion.
When
the
pre‐
ci‐
sion
is
miss‐
ing,
six
dig‐
its
are
pro‐
duced;
if
the
pre‐
ci‐
sion
is
0,
no
radix
char‐
ac‐
ter
appears.
The
con‐
ver‐
sion
char‐
ac‐
ter
pro‐
duces
a
num‐
ber
with
intro‐
duc‐
ing
the
expo‐
nent
instead
of
The
expo‐
nent
always
con‐
tains
at
least
two
dig‐
its.
How‐
ever,
if
the
value
to
be
printed
requires
an
expo‐
nent
greater
than
two
dig‐
its,
addi‐
tional
expo‐
nent
dig‐
its
are
printed
as
nec‐
es‐
sary.
The
float‐
ing-
point-
num‐
ber
argu‐
ment
is
printed
in
style or
(or
int
style
in
the
case
of
a
con‐
ver‐
sion
char‐
ac‐
ter),
with
the
pre‐
ci‐
sion
spec‐
i‐
fy‐
ing
the
num‐
ber
of
sig‐
nif‐
i‐
cant
dig‐
its.
The
style
used
depends
on
the
value
con‐
verted;
style
is
used
only
if
the
expo‐
nent
result‐
ing
from
the
con‐
ver‐
sion
is
less
than
or
greater
than
or
equal
to
the
pre‐
ci‐
sion.
Trail‐
ing
zeros
are
remove
from
the
result.
A
radix
char‐
ac‐
ter
appears
only
if
it
is
fol‐
lowed
by
a
digit.
The
first
byte
of
the
argu‐
ment
is
printed.
The
argu‐
ment
is
taken
to
be
a
string, and
char‐
ac‐
ters
from
the
string
are
printed
until
the
end
of
the
string
or
the
num‐
ber
of
bytes
indi‐
cated
by
the
pre‐
ci‐
sion
spec‐
i‐
fi‐
ca‐
tion
of
the
argu‐
ment
is
reached.
If
the
pre‐
ci‐
sion
is
omit‐
ted
from
the
argu‐
ment,
it
is
inter‐
preted
as
infi‐
nite
and
all
char‐
ac‐
ters
up
to
the
end
of
the
string
are
printed.
Print
a char‐
ac‐
ter;
no
argu‐
ment
is
con‐
verted.
Sim‐
i‐
lar
to
the con‐
ver‐
sion
spec‐
i‐
fier,
except
that
the
string
can
con‐
tain
back‐
slash-
escape
sequences
which
are
then
con‐
verted
to
the
char‐
ac‐
ters
they
rep‐
re‐
sent.
will
cause
to
ignore
any
remain‐
ing
char‐
ac‐
ters
in
the
string
op‐
er‐
and
con‐
tain‐
ing
it,
any
remain‐
ing
string
op‐
er‐
ands
and
any
addi‐
tional
char‐
ac‐
ters
in
the
for‐
mat
op‐
er‐
and.
In
no
case
does
a
nonex‐
is‐
tent
or
insuf‐
fi‐
cient
field
width
cause
trun‐
ca‐
tion
of
a
field;
if
the
result
of
a
con‐
ver‐
sion
is
wider
than
the
field
width,
the
field
is
sim‐
ply
expanded
to
con‐
tain
the
con‐
ver‐
sion
result.
EXTERNAL INFLU‐
ENCES
Environment
Variables
deter‐
mines the
interpre‐
tation of
arg as
single
and/or
multi-
byte
charac‐
ters.
deter‐
mines the
language
in which
messages
are dis‐
played.
If or is
not spec‐
ified in
the envi‐
ronment
or is set
to the
empty
string,
the value
of is
used as a
default
for each
unspeci‐
fied or
empty
variable.
If is not
specified
or is set
to the
empty
string, a
default
of "C"
(see
lang(5))
is used
instead
of
If any
interna‐
tional‐
ization
variable
contains
an
invalid
setting,
printf
behaves
as if all
interna‐
tional‐
ization
variables
are set
to "C".
See envi‐
ron(5).
International
Code Set
Support
Single
and
multi-
byte
character
code sets
are sup‐
ported.
RETURN VALUE
exits
with one
of the
following
values:
Suc‐
cess‐
ful
com‐
ple‐
tion.
Errors
occurred;
the
exit
value
is
increased
by
one
for
each
error
that
occurred
up
to
a
max‐
i‐
mum
of
255.
DIAGNOSTICS
If an
argument
cannot be
converted
into a
form
suitable
for the
corre‐
sponding
conver‐
sion
specifi‐
cation,
or for
any other
reason
cannot be
correctly
printed,
a diag‐
nostic
message
is
printed
to stan‐
dard
error,
the argu‐
ment is
output as
a string
form as
it was
given on
the com‐
mand
line, and
the exit
value is
incre‐
mented.
EXAMPLES
The fol‐
lowing
command
prints
the num‐
ber 123
in octal,
hexadeci‐
mal and
floating
point
formats
in their
alternate
form
printf "%#o, %#x, %#X, %#f, %#g, %#e\n" 123 123 123 123 123 123
resulting
in the
following
output
Print the
outputs
with
their
corre‐
sponding
field
widths
and pre‐
cision:
printf "%.6d, %10.6d, %.6f, %.6e, %.6s\n" 123 123 1.23 123.4 MoreThanSix
resulting
in the
following
output
SEE ALSO
echo(1),
printf(3S).
STANDARDS CON‐
FORMANCE
printf(1)
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