Operating System Facilities.
Returns an approximation of the amount in seconds of CPU time used by the program.
Returns the number of seconds from time
t1 to time
In POSIX, Windows, and some other systems, this value is exactly
This function is equivalent to the C function system. It passes command to be executed by an operating system shell. It returns a status code, which is system-dependent. If command is absent, then it returns nonzero if a shell is available and zero otherwise.
Calls the C function exit, with an optional code, to terminate the host program. The default value for code is the success code.
Returns the value of the process environment variable
if the variable is not defined.
Deletes the file or directory with the given name. Directories must be empty to be removed.
Renames file or directory named
Sets the current locale of the program.
Returns the current time when called without arguments, or a time representing the date and time specified by the given table.
The returned value is a number, whose meaning depends on your system. In POSIX, Windows, and some other systems, this number counts the number of seconds since some given start time (the "epoch"). In other systems, the meaning is not specified, and the number returned by time can be used only as an argument to date and difftime.