#include <limits.h>
| 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) |