Perl Pocket Reference, 5th Edition

System Interaction

alarm expr†

Schedules a SIGALRM signal to be delivered after expr seconds. If expr is zero, cancels a pending timer.

chdir [ expr ]

Changes the working directory. expr can be a file name or a handle. Uses $ENV{HOME} or $ENV{LOGNAME} if expr is omitted.

chroot filename†

Changes the root directory for the process and any future children.

die [ list ]

Prints the value of list to STDERR and exits with value $!(if nonzero), or ($?>> 8) (if nonzero), or 255. list defaults to the text "Died".

Included in the message are the name and line number of the program and the current line of input read. This information is suppressed if the last character of the last element of list is a newline.

Inside an eval, the error message is stuffed into $@, and the eval is terminated returning undef. This makes die and eval the way to raise and catch exceptions.

exec [ program ] list

Executes the system command in list; does not return. program can be used to explictly designate the program to execute the command.

exit [ expr ]

Exits immediately with the value of expr, which defaults to zero. Calls END routines and object destructors before exiting.

fork

Does a fork syscall. Returns the process ID of the child to the parent process (or undef on failure) and zero to the child process.

getlogin

Returns the current login name as known by the system. If it returns false, use getpwuid.

getpgrp [ pid ]

Returns the process group for process pid. If pid is zero, or omitted, uses the current process.

getppid ...