LIMITS(4) LIMITS(4)
NAME
limits - file header for implementation-specific constants
SYNOPSIS
#include <limits.h>
DESCRIPTION
The header file <limits.h> is a list of magnitude
limitations imposed by a specific implementation of the
operating system. All values are specified in decimal.
#define ARG_MAX 5120 /* tradional max for exec args */
#define CHAR_BIT 8 /* # of bits in a "char" */
#define CHAR_MAX 255 /* max integer value of a "char" */
#define CHAR_MIN 0 /* min integer value of a "char" */
#define CHILD_MAX 25 /* max # of processes per user id */
#define CLK_TCK 100 /* # of clock ticks per second */
#define DBL_DIG 16 /* digits of precision of a "double" */
#define DBL_MAX 1.79769313486231470e+308 /*max decimal value of a "double"*/
#define DBL_MIN 4.94065645841246544e-324 /*min decimal value of a "double"*/
#define FCHR_MAX 1048576 /* max size of a file in bytes */
#define FLT_DIG 7 /* digits of precision of a "float" */
#define FLT_MAX 3.40282346638528860e+38 /*max decimal value of a "float" */
#define FLT_MIN 1.40129846432481707e-45 /*min decimal value of a "float" */
/*#define HUGE_VAL 3.40282346638528860e+38 /*error value returned by Math lib*/
#define HUGE_VAL _MaXfLoA
extern float HUGE_VAL _MaXfLoA
#define INT_MAX 2147483647 /* max decimal value of an "int" */
#define UINT_MAX 4294967295 /* max decimal value of an "unsigned" */
#define INT_MIN -2147483648 /* min decimal value of an "int" */
#define LINK_MAX 1024 /* max # of links to a single file */
/* was 1024 - changed to comply with */
/* BCS 9 8.1 */
#define LONG_MAX 2147483647 /* max decimal value of a "long" */
#define LONG_MIN -2147483648 /* min decimal value of a "long" */
#define ULONG_MAX 4294967295 /* max decimal value of an "unsigned" */
#define NAME_MAX 14 /* max # of characters in a file name */
#define OPEN_MAX 25 /* max # of files a process can have open */
/* was 80 - changed to comply with */
/* BCS 9 8.1 */
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LIMITS(4) LIMITS(4)
#define PASS_MAX 8 /* max # of characters in a password */
#define PATH_MAX 256 /* max # of characters in a path name */
#define PID_MAX 30000 /* max value for a process ID */
#define PIPE_BUF 512 /* max # bytes atomic in write to a pipe */
/* was 5120 - changed to comply with */
/* BCS 9 8.1 */
#define PIPE_MAX 5120 /* max # bytes written to a pipe in a write */
#define SHRT_MAX 32767 /* max decimal value of a "short" */
#define SHRT_MIN -32767 /* min decimal value of a "short" */
#define STD_BLK 1024 /* # bytes in a physical I/O block */
#define SYS_NMLN 9 /* # of chars in uname-returned strings */
#define UID_MAX 60000 /* max value for a user or group ID */
#define USI_MAX UINT_MAX /* max decimal value of an "unsigned" */
#define WORD_BIT 32 /* # of bits in a "word" or "int" */
#define MAX_CANON 255 /* max # of bytes in a teminal */
* canonical input line */
* (POSIX 13 2.9.5 & BCS 9 8.1) */
#define MAX_INPUT 255 /* Minimum # of bytes for which */
/* for which space is guaranteed in */
/* a terminal input queue. */
#define NGROUPS_MAX 16 /* Minimum maximum number of simultaneous */
/* supplementary group ID's per */
/* process */
/*
* POSIX limits - actual values for this system available from sysconf()
*/
#define _POSIX_ARG_MAX 4096 /* length of the arguments for exec */
/* in bytes including environment */
/* data */
#define _POSIX_CHILD_MAX 6 /* The number of simultaneous procs */
/* per user ID */
#define _POSIX_LINK_MAX 8 /* The value of a file's link count */
#define _POSIX_MAX_CANON 255 /* The number of bytes in a terminal */
/* canonical input queue */
#define _POSIX_MAX_INPUT 255 /* The number of bytes for which */
/* space is guaranteed to be */
/* available for terminal input queue */
#define _POSIX_NAME_MAX 14 /* Number of bytes in a filename */
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LIMITS(4) LIMITS(4)
#define _POSIX_NGROUPS_MAX 0 /* Number of simultaneous supp. */
/* group ID's per process */
#define _POSIX_OPEN_MAX 16 /* The number of files that one proc */
/* can have open at a time */
#define _POSIX_PATH_MAX 255 /* Max number of bytes in a pathname */
#define _POSIX_PIPE_BUF 512 /* Number of bytes guaranteed to be */
/* written atomically to a pipe */
Page 3 May 1989