Command-line parameters in Shell Script?

Question

I am trying to include this

du -s *|awk '{ if ($1 > 3000) print }'

in a shell script, but I want to parameterize the 3000. However, since the $1 is already being used, I'm not sure what to do. This was a total failure:

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

How can I pass a parameter in place of 3000 in the first script above?

@ghostdog74, well this `size=$1; du -s *|awk '{ $1>size }' doesn't work... not sure what your comment means — Dan Rosenstark
– Dan Rosenstark, Commented Mar 1, 2010 at 12:14
i mean in awk, {if ($1 > $size) print} is the same as $1>size. see my answer for clearer picture. — ghostdog74
– ghostdog74, Commented Mar 1, 2010 at 23:38

ghostdog74 · Accepted Answer · 2010-03-01 11:44:51Z

4

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'

answered Mar 1, 2010 at 11:44

ghostdog74

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2 Comments

Idelic Over a year ago

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

ghostdog74 Over a year ago

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

Ignacio Vazquez-Abrams · Accepted Answer · 2010-03-01 11:27:46Z

3

Single quotes inhibit expansion, so:

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

answered Mar 1, 2010 at 11:27

Ignacio Vazquez-Abrams

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2 Comments

Dan Rosenstark Over a year ago

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

Ignacio Vazquez-Abrams Over a year ago

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.

a'r · Accepted Answer · 2010-03-01 11:28:38Z

3

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

answered Mar 1, 2010 at 11:28

a'r

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2 Comments

a'r Over a year ago

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

Dan Rosenstark Over a year ago

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

mouviciel · Accepted Answer · 2010-03-01 11:53:44Z

1

You can set awk variables on its command line:

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

answered Mar 1, 2010 at 11:53

mouviciel

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2 Comments

ghostdog74 Over a year ago

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

Dan Rosenstark Over a year ago

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

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