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limits(4)

NAME | SYNOPSIS | DESCRIPTION | SEE ALSO

NAME

limits- header for implementation-specific constants

SYNOPSIS

#include <limits.h>

DESCRIPTION

The header <limits.h> is a list of minimal magnitude limitations 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 canonical 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 password */
PATH_MAX	1024	/* max # of characters in a path name */
PID_MAX	99999	/* 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 pathname */
_POSIX_PIPE_BUF	512	/* max # of bytes atomic in write to a pipe */