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Command-line parameters in Shell Script?

Answer 1

+2 A:

Single quotes inhibit expansion, so:

du -s *|awk '{ if ($1 > '"$1"') print }'

Ignacio Vazquez-Abrams 2010-03-01 11:27:46

this is a great answer. could you include why it's better/worse/same as `du -s *|awk '{ if ($1 > '$1') print }'`?

Yar 2010-03-01 12:11:13

If the first argument contains a space (it *shouldn't*, but I prefer not to hope things go right) then omitting the double quotes will cause awk to not necessarily work as desired.

Ignacio Vazquez-Abrams 2010-03-01 12:21:29

Answer 2

+3 A:

size=$1
du -s *|awk '{ if ($1 > '$size') print }'

ar 2010-03-01 11:28:38

this is cool, thanks! Also works with '$1' of course.

Yar 2010-03-01 12:01:41

Be a little careful, as passing a parameter with a space in it will cause this to fail. This may of course be desirable.

ar 2010-03-01 12:07:05

But using your answer you can also just nix the $size and use $1 where you used $size. Anything wrong with that option?

Yar 2010-03-01 12:16:05

Answer 3

+4 A:

when passing shell variables to awk, try to use the -v option of awk as much as possible. This will be "cleaner" than having quotes all around

size="$1"
du -s *| awk -v size="$size" '$1>size'

ghostdog74 2010-03-01 11:44:51

The quotes in size="$1" are unnecessary. Simple variable assignments (FOO=$BAR) don't need quotes.

Idelic 2010-03-01 18:09:48

its my habit sometimes. no harm putting it in anyways.

ghostdog74 2010-03-01 23:36:33

Answer 4

+1 A:

You can set awk variables on its command line:

du -s * | awk '{ if ($1 > threshold) print }' threshold=$1

mouviciel 2010-03-01 11:53:44

only exception using this method is that `threshold` will not have value in BEGIN{} block.

ghostdog74 2010-03-01 12:01:02

interesting, cool way to do it.

Yar 2010-03-01 12:01:08

@ghostdog74 what do you miss without the BEGIN{} block?

Yar 2010-03-02 09:28:32

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Command-line parameters in Shell Script?

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