limits(4) limits(4)
NAME
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 5120 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 2147483647 max value of an "int"
INT_MIN -2147483648 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 2147483647 max value of a "long int"
LONG_MIN -2147483648 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
Copyright 1994 Novell, Inc. Page 1
limits(4) limits(4)
NZERO 20 default process priority
OPEN_MAX 60 max # of files a process can have
open
PASS_MAX 8 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 14 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 60000 max value for a user or group ID
UINT_MAX 4294967295 max value of an "unsigned int"
ULONG_MAX 4294967295 max value of an "unsigned long
int"
USHRT_MAX 65535 max value of an "unsigned short
int"
Copyright 1994 Novell, Inc. Page 2
limits(4) limits(4)
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)
Copyright 1994 Novell, Inc. Page 3