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0 Restore original settings. 1 Change to cooked mode. 2 Change to cooked mode with echo off. (Good for passwords) 3 Change to cbreak mode. 4 Change to raw mode. 5 Change to ultra-raw mode. (LF to CR/LF translation turned off) Or, you may use the synonyms: restore normal noecho cbreak raw ultra-raw
These functions are automatically applied to the STDIN handle if no other handle is supplied. Modes 0 and 5 have some special properties worth mentioning: not only will mode 0 restore original settings, but it cause the next ReadMode call to save a new set of default settings. Mode 5 is similar to mode 4, except no CR/LF translation is performed, and if possible, parity will be disabled (only if not being used by the terminal, however.)
If you are executing another program that may be changing the terminal mode, you will either want to say
ReadMode 1 system('someprogram'); ReadMode 1; which resets the settings after the program has run, or:
$somemode=1; ReadMode 0; system('someprogram'); ReadMode 1; which records any changes the program may have made, before resetting the mode.
0 Perform a normal read using getc -1 Perform a non-blocked read >0 Perform a timed read
(If the filehandle is not supplied, it will default to STDIN.) If there is
nothing waiting in the buffer during a non-blocked read, then undef will be
returned. Note that if the OS does not provide any known mechanism for
non-blocking reads, then a ReadKey -1
can die with a fatal error. This will hopefully not be common.
If MODE is greater then zero, then ReadKey will use it as a timeout value
in seconds (fractional seconds are allowed), and won't return undef
until that time expires. (Note, again, that some OS's may not support this
timeout behaviour.) If MODE is less then zero, then this is treated as a
timeout of zero, and thus will return immediately if no character is
waiting. A MODE of zero, however, will act like a normal getc.
0 Perform a normal read using scalar(<FileHandle>) -1 Perform a non-blocked read >0 Perform a timed read
If there is nothing waiting in the buffer during a non-blocked read, then
undef will be returned. Note that if the OS does not provide any known
mechanism for non-blocking reads, then a ReadLine 1
can die with a fatal error. This will hopefully not be common. Note that a
non-blocking test is only performed for the first character in the line,
not the entire line. This call will probably not do what you assume, especially with ReadMode's higher then 1. For example,
pressing Space and then Backspace would appear to leave you where you
started, but any timeouts would now be suspended.
Each key will be an entry from the following list:
DISCARD DSUSPEND EOF EOL EOL2 ERASE ERASEWORD INTERRUPT KILL MIN QUIT QUOTENEXT REPRINT START STATUS STOP SUSPEND SWITCH TIME
Thus, the following will always return the current interrupt character, regardless of platform.
%keys = GetControlChars; $int = $keys{INTERRUPT};
%cchars = GetControlChars(); @cnames = keys %cchars;