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Topic: Cond statements, BASH

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curaga

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Posted: Sep. 09 2007,15:50

Or even more tech: both [ and test are actually the same common shell builtin, atleast bash and ash have it. So when invoked just like that, [ something or test something, they are the same thing, but as binaries, /usr/bin/[ something, they would be different ;)

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roberts

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Posted: Sep. 09 2007,16:22

When struggling with bash syntax it is often helpful to preuse existing bash scripts, i.e., /etc/init.d/knoppix-autoconfig and/or /etc/init.d/dsl.config

jpeters

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Posted: Sep. 09 2007,21:34

I'm always impressed by the level of expertise on this board. Although I'm not sure where someone learns about binaries related to
"[" vs. "test" , I'm duly impressed and enlightened. I'm studying knoppix-autoconfig right now with vim, where spacing is clear.

mikshaw

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Posted: Sep. 09 2007,23:37

Quote

Although I'm not sure where someone learns about binaries related to
"[" vs. "test"

I can't speak for others, but in my case it comes from constant poking and prodding at things to see what color they bleed.

When it comes to "[" specifically, I just thought it was very odd to see that character listed as a filename when i did "ls /usr/bin", so I had to find out what was up. This is kind of an unusual situation because "man [" and "[ --help" don't work. However, "/usr/bin/[ --help" does work:

Code Sample

/usr/bin/[ --help
Usage: test EXPRESSION
or: [ EXPRESSION ]
or: [ OPTION
Exit with the status determined by EXPRESSION.

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http://www.tldp.org/LDP/intro-linux/html/index.html

^thehatsrule^ Offline

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Posted: Sep. 10 2007,00:39

In DSL, it looks like [ is a symlink to test. However, as curaga pointed out, it's also a bash/ash built-in, so removing it could save a couple KB -- unless something else requires it? (and put it in gnu-utils, if it isn't already in there?)

Quote

This is kind of an unusual situation because "man [" and "[ --help" don't work.

I'd guess that the shell would try to parse that... or try to use the built-in function (hence the use of the full path)

15 replies since Sep. 08 2007,19:00

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