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#include <unistd.h>
The following symbolic constants are defined for the access function [see access(2) ]:
| R_OK Test for read permission |
| W_OK Test for write permission |
| X_OK Test for execute (search) permission |
| F_OK Test for existence of file |
The constants F_OK, R_OK, W_OK, and X_OK, and the expressions R_OK|W_OK, R_OK|X_OK, and R_OK|W_OK|X_OK all have distinct values.
Declares the constant
| NULL | null pointer |
The following symbolic constants are defined for the lockf function [see lockf(3C) ]:
| F_ULOCK Unlock a previously locked region |
| F_LOCK Lock a region for exclusive use |
| F_TLOCK Test and lock a region for exclusive use |
| F_TEST Test a region for other processes locks |
The following symbolic constants are defined for the lseek [see lseek(2) ] and fcntl [see fcntl(2) ] functions (they have distinct values):
| SEEK_SET Set file offset to offset |
| SEEK_CUR Set file offset to current plus offset |
| SEEK_END Set file offset to EOF plus offset |
The following symbolic constants are defined (with fixed values):
| _POSIX_VERSION | Integer value indicating version |
| of the POSIX standard | |
| _XOPEN_VERSION | integer value indicating version of the XPG |
| to which system is compliant |
The following symbolic constants are defined to indicate that the option is present:
| _POSIX_JOB_CONTROL | implementation supports job control |
| _POSIX_SAVED_IDS | the exec functions (see exec(2) ) |
| save | the effective user and group |
| _POSIX_VDISABLE | terminal special characters defined in |
| <termios.h> (see termio(7I) ) can be | |
| disabled using this character |
The following symbolic constants are defined for sysconf (see sysconf(3C) ):
| _SC_ARG_MAX |
| _SC_CHILD_MAX |
| _SC_CLK_TCK |
| _SC_JOB_CONTROL |
| _SC_NGROUPS_MAX |
| _SC_OPEN_MAX |
| _SC_PAGESIZE |
| _SC_PASS_MAX |
| _SC_SAVED_IDS |
| _SC_VERSION |
| _SC_XOPEN_VERSION |
The following symbolic constants are defined for pathconf (see fpathconf(2) ):
| _PC_CHOWN_RESTRICTED |
| _PC_LINK_MAX |
| _PC_MAX_CANON |
| _PC_MAX_INPUT |
| _PC_NAME_MAX |
| _PC_NO_TRUNC |
| _PC_PATH_MAX |
| _PC_PIPE_BUF |
| _PC_VDISABLE |
The following symbolic constants are defined for file streams:
| STDIN_FILENO | File number of stdin. It is 0. |
| STDOUT_FILENO | File number of stout. It is 1. |
| STDERR_FILENO | File number of stderr. It is 2. |
The following pathnames are defined:
| GF_PATH | Pathname of the group file. |
| PF_PATH | Pathname of the passwd file. |
The following values for constants are defined:
| _POSIX_VERSION | 199009L |
| _XOPEN_VERSION | 3 |