limits(4)
NAME
limits - header for implementation-specific constants
SYNOPSIS
#include <limits.h>
DESCRIPTION
The header <limits.h> is a list of minimal magnitude limita-
tions imposed by a specific implementation of the operating
system.
_ARG_MAX32 1048320 /* max length of arguments to exec
32-bit program */
_ARG_MAX64 2096640 /* max length of arguments to exec
64-bit program */
CHAR_BIT 8 /* max # of bits in a char */
CHAR_MAX 255 /* max value of a char */
CHAR_MIN 0 /* min value of a char */
CHILD_MAX 25 /* max # of processes per user id
*/
CLK_TCK _sysconf(3) /* clock ticks per second */
DBL_DIG 15 /* digits of precision of a double
*/
DBL_MAX 1.7976931348623157E+308 /* max decimal value of a double*/
DBL_MIN 2.2250738585072014E-308 /* min decimal value of a double*/
FCHR_MAX 1048576 /* historical default file size
limit in bytes */
FLT_DIG 6 /* digits of precision of a float
*/
FLT_MAX 3.40282347e+38F /* max decimal value of a float */
FLT_MIN 1.17549435E-38F /* min decimal value of a float */
INT_MAX 2147483647 /* max value of an int */
INT_MIN (-2147483647-1) /* min value of an int */
LINK_MAX 1000 /* max # of links to a single file
*/
LOGNAME_MAX 8 /* max # of characters in a login
name */
LONG_BIT 32 /* # of bits in a long */
LONG_MAX 2147483647L /* max value of a long int if
_ILP32 defined */
9223372036854775807L /* max value of a long int if _LP64
defined */
LONG_MIN (-2147483647-1L) /* min value of a long int if
_ILP32 defined */
(-9223372036854775807L-1L) /* min value of a long int if _LP64
defined */
MAX_CANON 256 /* max bytes in a line for canoni-
cal processing */
MAX_INPUT 512 /* max size of a char input buffer
*/
MB_LEN_MAX 5 /* max # of bytes in a multibyte
character */
NAME_MAX 14 /* max # of characters in a file
name */
NGROUPS_MAX 16 /* max # of groups for a user */
NL_ARGMAX 9 /* max value of "digit" in calls to
the
NLS printf() and scanf() */
NL_LANGMAX 14 /* max # of bytes in a LANG name */
NL_MSGMAX 32767 /* max message number */
NL_NMAX 1 /* max # of bytes in N-to-1 mapping
characters */
NL_SETMAX 255 /* max set number */
NL_TEXTMAX 255 /* max # of bytes in a message
string */
NZERO 20 /* default process priority */
OPEN_MAX 20 /* max # of files a process can
have open */
PASS_MAX 8 /* max # of characters in a pass-
word */
PATH_MAX 1024 /* max # of characters in a path
name */
PID_MAX 999999 /* max value for a process ID */
PIPE_BUF 5120 /* max # bytes atomic in write to a
pipe */
PIPE_MAX 5120 /* max # bytes written to a pipe in
a write */
SCHAR_MAX 127 /* max value of a "signed char" */
SCHAR_MIN (-128) /* min value of a "signed char" */
SHRT_MAX 32767 /* max value of a "short int" */
SHRT_MIN (-32768) /* min value of a "short int" */
STD_BLK 1024 /* # bytes in a physical I/O block
*/
SYS_NMLN 257 /* 4.0 size of utsname elements */
/* also defined in sys/utsname.h */
SYSPID_MAX 1 /* max pid of system processes */
TMP_MAX 17576 /* max # of unique names generated
by tmpnam */
UCHAR_MAX 255 /* max value of an "unsigned char"
*/
UID_MAX 2147483647 /* max value for a user or group ID
*/
UINT_MAX 4294967295 /* max value of an "unsigned int"
*/
ULONG_MAX 4294967295UL /* max value of an "unsigned long
int" if _ILP32 defined */
18446744073709551615UL /* max value of an "unsigned long
int" if _LP64 defined */
USHRT_MAX 65535 /* max value of an "unsigned short
int" */
USI_MAX 4294967295 /* max decimal value of an
"unsigned" */
WORD_BIT 32 /* # of bits in a word or int */
The following POSIX definitions are the most restrictive
values to be used by a POSIX-conforming application (see
standards(5)). Conforming implementations shall provide
values at least this large.
_POSIX_ARG_MAX 4096 /* max length of arguments to exec
*/
_POSIX_CHILD_MAX 6 /* max # of processes per user ID
*/
_POSIX_LINK_MAX 8 /* max # of links to a single file
*/
_POSIX_MAX_CANON 255 /* max # of bytes in a line of
input */
_POSIX_MAX_INPUT 255 /* max # of bytes in terminal
input queue */
_POSIX_NAME_MAX 14 /* # of bytes in a filename */
_POSIX_NGROUPS_MAX 0 /* max # of groups in a process */
_POSIX_OPEN_MAX 16 /* max # of files a process can
have open */
_POSIX_PATH_MAX 255 /* max # of characters in a path-
name */
_POSIX_PIPE_BUF 512 /* max # of bytes atomic in write
to a pipe */
SEE ALSO
standards(5)
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