DOC HOME SITE MAP MAN PAGES GNU INFO SEARCH PRINT BOOK
 

limits(4)

limits -- header file for implementation-specific constants

Synopsis

   #include <limits.h>

Description

The header file limits.h is a list of minimal magnitude limitations imposed by a specific implementation of the operating system. The values listed below are subject to change.

ARG_MAX 10240 max length of arguments to exec
CHAR_BIT 8 max # of bits in a "char"
CHAR_MAX 127 max value of a "char"
CHAR_MIN -128 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"
FLT_DIG 6 digits of precision of a "float"
FLT_MAX 3.40282347e+38F max decimal value of a "float"
INT_MAX 0x7fffffff max value of an "int"
INT_MIN (-INT_MAX-1) min value of an "int"
LINK_MAX 1000 max # of links to a single file
LLONG_MAX 0x7fffffffffffffff max value of a "signed long long"
LLONG_MIN (-LLONG_MAX-1) min value of a "signed long long"
LOGNAME_MAX 8 max # of characters in a login name
LONG_BIT 32 # of bits in a "long"
LONG_MAX 0x7fffffffffffffff max value of a "long int"
LONG_MIN (-LONG_MAX-1) min value of a "long int"
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 4096 max # of bytes in a message string
NZERO 20 default process priority
OPEN_MAX 60 max # of files a process can have open
PASS_MAX 80 max # of characters in a password
BC_BASE_MAX 99 max obase values bc utility allows
BC_SCALE_MAX 99 max scale value bc utility allows
BC_DIM_MAX 2048 max # of elements allowed in a bc utility array
BC_STRING_MAX 1000 max length of a bc utility string constant
COLL_WEIGHTS_MAX 2 max # weights assignable to an entry of LC_COLLATE
EXPR_NEST_MAX 32 max # of expressions allowed to be nested within parentheses by the expr utility
LINE_MAX 2048 max byte length of the utility's input line when the utility is processing text files
RE_DUP_MAX 255 max # repeated occurrences of a regexp permitted when using m,n
CHARCLASS_NAME_MAX 100 max # bytes character class name can have
PATH_MAX 1024 max # of characters in a path name
PID_MAX 30000 max value for a process ID
PIPE_BUF 5120 max # bytes atomic in write to a pipe
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"
SSIZE_MAX INT_MAX max value of an "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 60002 max value for a user or group ID
UINT_MAX 0xffffffff max value of an "unsigned int"
ULLONG_MAX 0xffffffffffffffff max value of an "unsigned long long"
ULONG_MAX 0xffffffffffffffff max value of an "unsigned long int"
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" 

 ARG_MAX              10240                     max length of arguments to exec
 CHAR_BIT             8                         max # of bits in a "char"
 CHAR_MAX             127                       max value of a "char"
 CHAR_MIN             -128                      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"
 FLT_DIG              6                         digits of precision of a "float"
 FLT_MAX              3.40282347e+38F           max decimal value of a "float"
 INT_MAX              0x7fffffff                max value of an "int"
 INT_MIN              (-INT_MAX-1)              min value of an "int"
 LINK_MAX             1000                      max # of links to a single file
 LLONG_MAX            0x7fffffffffffffff        max value of a "signed long long"
 LLONG_MIN            (-LLONG_MAX-1)            min value of a "signed long long"
 LOGNAME_MAX          8                         max # of characters in a login name
 LONG_BIT             32                        # of bits in a "long"
 LONG_MAX             0x7fffffffffffffff        max value of a "long int"
 LONG_MIN             (-LONG_MAX-1)             min value of a "long int"
 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           4096                      max # of bytes in a message string
 NZERO                20                        default process priority
 OPEN_MAX             60                        max # of files a process can have
                                                open
 PASS_MAX             80                        max # of characters in a password
 BC_BASE_MAX          99                        max obase values bc utility allows
 BC_SCALE_MAX         99                        max scale value bc utility allows
 BC_DIM_MAX           2048                      max # of elements allowed in a bc
                                                utility array
 BC_STRING_MAX        1000                      max length of a bc utility string
                                                constant
 COLL_WEIGHTS_MAX     2                         max # weights assignable to an entry
                                                of LC_COLLATE
 EXPR_NEST_MAX        32                        max # of expressions allowed to be
                                                nested within parentheses by the
                                                expr utility
 LINE_MAX             2048                      max byte length of the utility's
                                                input line when the utility is
                                                processing text files
 RE_DUP_MAX           255                       max # repeated occurrences of a
                                                regexp permitted when using m,n
 CHARCLASS_NAME_MAX   100                       max # bytes character class name can
                                                have
 PATH_MAX             1024                      max # of characters in a path name
 PID_MAX              30000                     max value for a process ID
 PIPE_BUF             5120                      max # bytes atomic in write to a
                                                pipe
 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"
 SSIZE_MAX            INT_MAX                   max value of an "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              60002                     max value for a user or group ID
 UINT_MAX             0xffffffff                max value of an "unsigned int"
 ULLONG_MAX           0xffffffffffffffff        max value of an "unsigned long long"
 ULONG_MAX            0xffffffffffffffff        max value of an "unsigned long int"
 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 conformant application. 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
_POSIX_SSIZE_MAX 32767 min value stored in object of type ssize_t
_POSIX_STREAM_MAX 8 min number of streams (stdio) that one process can have open at a time
_POSIX_TZNAME_MAX 3 max number of bytes supported for name of a timezone (not the TZ variable) 

 _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
 _POSIX_SSIZE_MAX     32767        min value
                                   stored in
                                   object of type
                                   ssize_t
 _POSIX_STREAM_MAX    8            min number of
                                   streams (stdio)
                                   that one
                                   process can
                                   have open at a
                                   time
 _POSIX_TZNAME_MAX    3            max number of
                                   bytes supported
                                   for name of a
                                   timezone (not
                                   the TZ
                                   variable)
© 2004 The SCO Group, Inc. All rights reserved.
UnixWare 7 Release 7.1.4 - 25 April 2004