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Tricking a Unix Commandline Program into Accepting a File Stream

Answer 1

+2 A:

bash lets you do this:

program <(otherprogram)

This uses the output of otherprogram as the contents of a file passed to program.

Ignacio Vazquez-Abrams 2010-03-09 05:48:23

wow, that's a really nice trick!!

hasen j 2010-03-09 05:51:49

That's pretty neat. What's it called, and is is possible to use if hte program accepts TWO different file paths? (something like diff)

Alan Storm 2010-03-09 06:06:26

Process substitution, and yes, you can use... up to 60 or so I think.

Ignacio Vazquez-Abrams 2010-03-09 06:09:18

Sweet (more info here for the curious http://tldp.org/LDP/abs/html/process-sub.html)

Alan Storm 2010-03-09 06:19:37

Piping a file into a process's stdin is not the same as a process taking a filename and explicitly opening that file.

Ether 2010-03-09 07:06:40

@Ether: Try again. This doesn't pipe it into stdin.

Ignacio Vazquez-Abrams 2010-03-09 07:11:11

Answer 2

+3 A:

You may be interested in named pipes:

mkfifo myPipe
program myPipe &
anotherProgram > myPipe

is equivalent to:

anotherProgram | program

mouviciel 2010-03-09 05:49:25

Answer 3

A:

if your program is not coded to accept standard input, it won't work even if you use named pipes or process substitution

2010-03-09 05:56:37

I think 1ch1gO is saying that using a named pipe will only work if the program is written to work on a stream. You can pass a named pipe as an argument, but if the program tries to seek it will very likely fail. Often, programmers are sloppy and do not check if a seek failed, so the program may fail in unusual ways.

William Pursell 2010-03-09 15:11:23

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Tricking a Unix Commandline Program into Accepting a File Stream

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