Separate Focus HTML for Basic Foil 78 Execution of UNIX Commands -- Filehandle Mechanism (Chapter 15 of Llama Book)

Basic HTML version of Foils prepared March 30 97

Foil 78 Execution of UNIX Commands -- Filehandle Mechanism (Chapter 15 of Llama Book)

From PERL4 Tutorial for CPS616 Computational Science for Information Age Course CPS616 -- February 1995. by Geoffrey C. Fox

1	open(WHOHANDLE, "who\|"); # opens WHOHANDLE for reading output of system call to who
2	the \| at right means we will be able to treat output of who as though we were reading it as a file
3	@whosaid = <WHOHANDLE> ; # defines an array whosaid holding output of who command
4	open(LPRHANDLE,"\|lpr -Pgcf"); # with \| at left opens lpr process so that if we write to filehandle LPRHANDLE it is as though we handed file to input of lpr print LPRHANDLE "This is a test\n"; # for example
5	close(LPRHANDLE); # waits until lpr command has finished and closes handle

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Page produced by wwwfoil on Sat Sep 6 1997

1	open(WHOHANDLE, "who\|"); # opens WHOHANDLE for reading output of system call to who
2	the \| at right means we will be able to treat output of who as though we were reading it as a file
3	@whosaid = <WHOHANDLE> ; # defines an array whosaid holding output of who command
4	open(LPRHANDLE,"\|lpr -Pgcf"); # with \| at left opens lpr process so that if we write to filehandle LPRHANDLE it is as though we handed file to input of lpr print LPRHANDLE "This is a test\n"; # for example
5	close(LPRHANDLE); # waits until lpr command has finished and closes handle