8.123 POSIX (Perl in a Nutshell)

8.123 POSIX

Provides access to standard POSIX 1003.1 identifiers: functions, classes, and constants. Can be used to import one or multiple symbols:

use POSIX;                        # import all symbols
use POSIX qw(setsid);             # import one symbol
use POSIX qw(:errno_h :fcntl_h);  # import sets of symbols

Functions listed as C-specific are not implemented.

_exit	Identical to C function `_exit(2)`
abort	Identical to C function `abort(3)`
abs	Identical to Perl's `abs` function
access	Determines accessibility of a file; returns `undef` on failure
acos	Identical to C function `acos(3)`
alarm	Identical to Perl's `alarm` function
asctime	Identical to C function `asctime(3)`
asin	Identical to C function `asin(3)`
assert	Similar to C macro `assert(3)`
atan	Identical to C function `atan(3)`
atan2	Identical to Perl's `atan2` function
atexit	C-specific; use `END {}`
atof	C-specific
atoi	C-specific
atol	C-specific
bsearch	Not supplied
calloc	C-specific
ceil	Identical to C function `ceil(3)`
chdir	Identical to Perl's `chdir` function
chmod	Identical to Perl's `chmod` function
chown	Identical to Perl's `chown` function
clearerr	Uses method `FileHandle::clearerr`
clock	Identical to C function `clock(3)`
close	Closes a file; returns `undef` on failure
closedir	Identical to Perl's `closedir` function
cos	Identical to Perl's `cos` function
cosh	Identical to C function `cosh(3)`
creat	Creates a new file
ctermid	Generates path name for the controlling terminal
ctime	Identical to C function `ctime(3)`
cuserid	Gets user's login name
difftime	Identical to C function `difftime(3)`
div	C-specific
dup	Similar to C function `dup(2)`; returns `undef` on failure
dup2	Similar to C function `dup2(2)`; returns `undef` on failure
errno	Returns the value of `errno`
execl	C-specific; use Perl's `exec`
execle	C-specific; use Perl's `exec`
execlp	C-specific; use Perl's `exec`
execv	C-specific; use Perl's `exec`
execve	C-specific; use Perl's `exec`
execvp	C-specific; use Perl's `exec`
exit	Identical to Perl's `exit` function
exp	Identical to Perl's `exp` function
fabs	Identical to Perl's `abs` function
fclose	Uses method `FileHandle::close`
fcntl	Identical to Perl's `fcntl` function
fdopen	Uses method `FileHandle::new_from_fd`
feof	Uses method `FileHandle::eof`
ferror	Uses method `FileHandle::error`
fflush	Uses method `FileHandle::flush`
fgetc	Uses method `FileHandle::getc`
fgetpos	Uses method `FileHandle::getpos`
fgets	Uses method `FileHandle::gets`
fileno	Uses method `FileHandle::fileno`
floor	Identical to C function `floor(3)`
fmod	Identical to C function `fmod(3)`
fopen	Uses method `FileHandle::open`
fork	Identical to Perl's `fork` function
fpathconf	Returns value of a configurable limit on a file or directory, or `undef` on failure
fprintf	C-specific; use Perl's `printf` function
fputc	C-specific; use Perl's `print` function
fputs	C-specific; use Perl's `print` function
fread	C-specific; use Perl's `read` function
free	C-specific
freopen	C-specific; use Perl's `open` function
frexp	Returns mantissa and exponent of a floating-point number
fscanf	C-specific; use `<>` and regular expressions
fseek	Uses method `FileHandle::seek`
fsetpos	Uses method `FileHandle::setpos`
fstat	Gets file status
ftell	Uses method `FileHandle::tell`
fwrite	C-specific; use Perl's `print` function
getc	Identical to Perl's `etc` function
getchar	Returns one character from STDIN
getcwd	Returns name of current working directory
getegid	Returns effective group ID (gid)
getenv	Returns value of the specified environment variable
geteuid	Returns the effective user ID (uid)
getgid	Returns the user's real group ID (gid)
getgrgid	Identical to Perl's `getgrgid` function
getgrnam	Identical to Perl's `getgrnam` function
getgroups	Returns ids of the user's supplementary groups
getlogin	Identical to Perl's `getlogin` function
getpgrp	Identical to Perl's `getpgrp` function
getpid	Returns ID of the process (pid)
getppid	Identical to Perl's `getppid` function
getpwnam	Identical to Perl's `getpwnam` function
getpwuid	Identical to Perl's `getpwuid` function
gets	Returns one line from STDIN
getuid	Returns user's ID (uid)
gmtime	Identical to Perl's `gmtime` function
isalnum	Identical to C function, but can apply to one character or a whole string
isalpha	Identical to C function, but can apply to one character or a whole string
isatty	Returns Boolean indicating whether the specified filehandle is connected to a TTY
iscntrl	Identical to C function, but can apply to one character or a whole string
isdigit	Identical to C function, but can apply to one character or a whole string
isgraph	Identical to C function, but can apply to one character or a whole string
islower	Identical to C function, but can apply to one character or a whole string
isprint	Identical to C function, but can apply to one character or a whole string
ispunct	Identical to C function, but can apply to one character or a whole string
isspace	Identical to C function, but can apply to one character or a whole string
isupper	Identical to C function, but can apply to one character or a whole string
isxdigit	Identical to C function, but can apply to one character or a whole string
kill	Identical to Perl's `kill` function
labs	C-specific; use Perl's `abs` function
ldexp	Identical to C function `ldexp(3)`
ldiv	C-specific; use division operator (`/`) and Perl's `int` function
link	Identical to Perl's `link` function
localeconv	Gets numeric formatting information. Returns reference to a hash containing the current locale formatting values.
localtime	Identical to Perl's `localtime` function
log	Identical to Perl's `log` function
log10	Identical to C function `log10(3)`
longjmp	C-specific; use Perl's `die` function
lseek	Moves the read/write file pointer; returns `undef` on failure
malloc	C-specific
mblen	Identical to C function `mblen(3)`
mbstowcs	Identical to C function `mbstowcs(3)`
mbtowc	Identical to C function `mbtowc(3)`
memchr	C-specific; use Perl's `index`
memcmp	C-specific; use `eq`
memcpy	C-specific; use `=`
memmove	C-specific; use `=`
memset	C-specific; use `x`
mkdir	Identical to Perl's `mkdir` function
mkfifo	Similar to C function `mkfifo(2)`; returns `undef` on failure
mktime	Converts date/time information to a calendar time; returns `undef` on failure
modf	Returns integral and fractional parts of a floating-point number
nice	Similar to C function `nice(3)`; returns `undef` on failure
offsetof	C-specific
open	Opens file for reading or writing; returns `undef` on failure
opendir	Opens directory for reading; returns `undef` on failure
pathconf	Retrieves value of a configurable limit on a file or directory; returns `undef` on failure
pause	Similar to C function `pause(3)`; returns `undef` on failure
perror	Identical to C function `perror(3)`
pipe	Creates an interprocess channel
pow	Computes `$x` raised to the power `$exponent`
printf	Prints specified arguments to STDOUT
putc	C-specific; use Perl's `print` function
putchar	C-specific; use Perl's `print` function
puts	C-specific; use Perl's `print` function
qsort	C-specific; use Perl's `sort` function
raise	Sends specified signal to current process
rand	Non-portable; use Perl's `rand` function
read	Reads from a file; returns `undef` on failure
readdir	Identical to Perl's `readdir` function
realloc	C-specific
remove	Identical to Perl's `unlink` function
rename	Identical to Perl's `rename` function
rewind	Seeks to beginning of file
rewinddir	Identical to Perl's `rewinddir` function
rmdir	Identical to Perl's `rmdir` function
scanf	C-specific; use `<>` and regular expressions
setgid	Sets real group id for this process
setjmp	C-specific; use `eval {}`
setlocale	Modifies and queries program's locale
setpgid	Similar to C function `setpgid(2)`; returns `undef` on failure
setsid	Identical to C function `setsid(8)`
setuid	Sets real user ID for this process
sigaction	Detailed signal management; returns `undef` on failure
siglongjmp	C-specific; use Perl's `die` function
sigpending	Examines blocked, pending signals and returns `undef` on failure
sigprocmask	Changes and/or examines this process's signal mask; returns `undef` on failure
sigsetjmp	C-specific; use `eval {}`
sigsuspend	Installs signal mask and suspends process until signal arrives; returns `undef` on failure
sin	Identical to Perl's `sin` function
sinh	Identical to C function `sinh(3)`
sleep	Identical to Perl's `sleep` function
sprintf	Identical to Perl's `sprintf` function
sqrt	Identical to Perl's `sqrt` function
srand	Identical to Perl's `srand` function
sscanf	C-specific; use regular expressions
stat	Identical to Perl's `stat` function
strcat	C-specific; use `.=`
strchr	C-specific; use `index`
strcmp	C-specific; use `eq`
strcoll	Identical to C function `strcoll(3)`
strcpy	C-specific; use `=`
strcspn	C-specific; use regular expressions
strerror	Returns error string for the specified `errno`
strftime	Converts date and time to string and returns the string
strlen	C-specific; use `length`
strncat	C-specific; use `.=` and/or `substr`
strncmp	C-specific; use `eq` and/or `substr`
strncpy	C-specific; use `=` and/or `substr`
stroul	C-specific
strpbrk	C-specific
strrchr	C-specific; use `rindex` and/or `substr`
strspn	C-specific
strstr	Identical to Perl's `index` function
strtod	C-specific
strtok	C-specific
strtol	C-specific
strtoul	C-specific
strxfrm	String transformation; returns the transformed string
sysconf	Retrieves values of system configurable variables; returns `undef` on failure
system	Identical to Perl's `system` function
tan	Identical to C function `tan(3)`
tanh	Identical to C function `tanh(3)`
tcdrain	Similar to C function `tcdrain(3)`; returns `undef` on failure
tcflow	Similar to C function `tcflow(3)`; returns `undef` on failure
tcflush	Similar to C function `tcflush(3)`; returns `undef` on failure
tcgetpgrp	Identical to C function `tcgetpgrp(3)`
tcsendbreak	Similar to C function `tcsendbreak(3)`; returns `undef` on failure
tcsetpgrp	Similar to C function `tcsetpgrp(3)`; returns `undef` on failure
time	Identical to Perl's `time` function
times	Returns, in clock ticks, elapsed realtime since some point in the past, user and system times for this process, and user and system times for child processes
tmpfile	Uses method `FileHandle::new_tmpfile`
tmpnam	Returns a name for a temporary file
tolower	Identical to Perl's `lc` function
toupper	Identical to Perl's `uc` function
ttyname	Identical to C function `ttyname(3)`
tzname	Retrieves time conversion information from the `tzname` variable
tzset	Identical to C function `tzset(3)`
umask	Identical to Perl's `umask` function
uname	Gets name of current operating system
ungetc	Uses method `FileHandle::ungetc`
unlink	Identical to Perl's `unlink` function
utime	Identical to Perl's `utime` function
vfprintf	C-specific
vprintf	C-specific
vsprintf	C-specific
wait	Identical to Perl's `wait` function
waitpid	Waits for child process to change state; identical to Perl's `waitpid` function
wcstombs	Identical to C function `wcstombs(3)`
wctomb	Identical to C function `wctomb(3)`
write	Writes to file; returns `undef` on failure

The following sections show the classes that are defined and their methods:

8.123.1 POSIX::SigAction

8.123.2 POSIX::SigSet

8.123.3 POSIX::Termios

8.123.4 Constants

The following constants are associated with the Termios class:

Baud rate values

B0  B75  B134 B200 B600  B1800 B4800 B19200
B50 B110 B150 B300 B1200 B2400 B9600 B38400

c_cc index values

VEOF VERASE VKILL VSUSP  VSTOP VTIME 
VEOL VINTR  VQUIT VSTART VMIN  NCCS

c_cflag field values

CLOCAL CSIZE CS6 CS8    HUPCL  PARODD
CREAD  CS5   CS7 CSTOPS PARENB

c_iflag field values

BRKINT IGNBRK IGNPAR INPCK  IXOFF PARMRK
ICRNL  IGNCR  INLCR  ISTRIP IXON

c_lflag field values

ECHO  ECHONL ISIG  
ECHOE ICANON NOFLSH
ECHOK IEXTEN TOSTOP

c_oflag field values

OPOST

Terminal interface values

TCSADRAIN TCIOFLUSH TCIFLUSH 
TCSANOW   TCOFLUSH  TCSAFLUSH 
TCOON     TCION     TCIOFF

The following are other constants defined in the POSIX module:

Pathname constants

_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

POSIX constants

_POSIX_ARG_MAX      _POSIX_CHILD_MAX  _POSIX_CHOWN_RESTRICTED 
_POSIX_JOB_CONTROL  _POSIX_LINK_MAX   _POSIX_MAX_CANON
_POSIX_MAX_INPUT    _POSIX_NAME_MAX   _POSIX_NGROUPS_MAX
_POSIX_NO_TRUNC     _POSIX_OPEN_MAX   _POSIX_PATH_MAX
_POSIX_PIPE_BUF     _POSIX_SAVED_IDS  _POSIX_SSIZE_MAX
_POSIX_STREAM_MAX   _POSIX_TZNAME_MAX _POSIX_VDISABLE  
_POSIX_VERSION

System configuration

_SC_ARG_MAX      _SC_CHILD_MAX  _SC_CLK_TCK    _SC_JOB_CONTROL
_SC_NGROUPS_MAX  _SC_OPEN_MAX   _SC_SAVED_IDS  _SC_STREAM_MAX
_SC_TZNAME_MAX   _SC_VERSION

Error constants

E2BIG   EACCES  EAGAIN    EBADF   EBUSY   ECHILD  EDEADLK
EDOM    EEXIST  EFAUL     EFBIG   EINTR   EINVAL  
EIO     EISDIR  EMFILE    EMLINK  ENAMETOOLONG    ENFILE  
ENODE   ENOENT  ENOEXEC   ENOLCK  ENOMEM  ENOSPC  
ENOSYS  ENOTDIR ENOTEMPTY ENOTTY  ENXIO   EPERM  
EPIPE   ERANGE  EROFS     ESPIPE  ESRCH   EXDEV

File control constants

FD_CLOEXEC  F_DUPFD    F_GETFD   F_GETFL  F_GETLK   F_OK
F_RDLCK     F_SETFD    F_SETFL   F_SETLK  F_SETLKW  F_UNLCK
F_WRLCK     O_ACCMODE  O_APPEND  O_CREAT  O_EXCL    O_NOCTTY
O_NONBLOCK  O_RDONLY   O_RDWR    O_TRUNC  O_WRONLY

Floating-point constants

DBL_DIG         DBL_EPSILON     DBL_MANT_DIG  DBL_MAX
DBL_MAX_10_EXP  DBL_MAX_EXP     DBL_MIN       DBL_MIN_10_EXP
DBL_MIN_EXP     FLT_DIG         FLT_EPSILON   FLT_MANT_DIG
FLT_MAX         FLT_MAX_10_EXP  FLT_MAX_EXP   FLT_MIN
FLT_MIN_10_EXP  FLT_MIN_EXP     FLT_RADIX     FLT_ROUNDS
LDBL_DIG        LDBL_EPSILON    LDBL_MANT_DIG LDBL_MAX
LDBL_MAX_10_EXP LDBL_MAX_EXP    LDBL_MIN      LDBL_MIN_10_EXP
LDBL_MIN_EXP

Limit constants

ARG_MAX    CHAR_BIT  CHAR_MAX    CHAR_MIN    CHILD_MAX
INT_MAX    INT_MIN   LINK_MAX    LONG_MAX    LONG_MIN
MAX_CANON  MAX_INPUT MB_LEN_MAX  NAME_MAX    NGROUPS_MAX
OPEN_MAX   PATH_MAX  PIPE_BUF    SCHAR_MAX   SCHAR_MIN
SHRT_MAX   SHRT_MIN  SSIZE_MAX   STREAM_MAX  TZNAME_MAX
UCHAR_MAX  UINT_MAX  ULONG_MAX   USHRT_MAX

Locale constants

LC_ALL  LC_COLLATE  LC_CTYPE  LC_MONETARY  LC_NUMERIC  LC_TIME

Math constants

HUGE_VAL

Signal constants

SA_NOCLDSTOP SIGABRT    SIGALRM    SIGCHLD  SIGCONT  SIGFPE
SIGHUP       SIGILL     SIGINT     SIGKILL  SIGPIPE  SIGQUIT
SIGSEGV      SIGSTOP    SIGTERM    SIGTSTP  SIGTTIN  SIGTTOU
SIGUSR1      SIGUSR2    SIG_BLOCK  SIG_DFL  SIG_ERR  SIG_IGN
SIG_SETMASK  SIG_UNBLOCK

Stat constants

S_IRGRP  S_IROTH  S_IRUSR  S_IRWXG  S_IRWXO  S_IRWXU  S_ISGID
S_ISUID  S_IWGRP  S_IWOTH  S_IWUSR  S_IXGRP  S_IXOTH  S_IXUSR

Stat macros

S_ISBLK  S_ISCHR  S_ISDIR  S_ISFIFO  S_ISREG

Stdlib constants

EXIT_FAILURE  EXIT_SUCCESS  MB_CUR_MAX  RAND_MAX

Stdio constants

BUFSIZ  EOF  FILENAME_MAX  L_ctermid  L_cuserid  L_tmpname  TMP_MAX

Time constants

CLK_TCK  CLOCKS_PER_SEC

Unistd constants

R_OK   SEEK_CUR  SEEK_END       SEEK_SET  STDIN_FILENO
STDOUT_FILENO    STRERR_FILENO  W_OK      X_OK

Wait constants

WNOHANG  WUNTRACED

Wait macros

WIFEXITED  WEXITSTATUS  WIFSIGNALED  WTERMSIG   WIFSTOPPED   WSTOPSIG


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