Re: xargs - is it possible to take each argument in to xargs and use in sed against a file?

From: Stephane Chazelas (stephane_at_artesyncp.com)
Date: 08/19/05 

Date: 19 Aug 2005 20:16:10 GMT

On 19 Aug 2005 12:56:46 -0700, Dundonald wrote:
[...]
> awk < $file '
> /$criteria/ && FNR > 1 {
> print last_line
> }
> {
> last_line = $0
> }'

You need to have the shell pass the variable to awk.

A good way to do this is making the variable an environment
variable have use awk's special ENVIRON associative array.

criteria_ENV=$criteria awk < "$file" '
  $0 ~ ENVIRON["criteria_ENV"] {
    print last_line
  }
  {
    last_line = $0
  }'

You need a POSIX conformant awk. That should be fine on every
recent Unices, except on Solaris where you need to make sure
/usr/xpg4/bin/awk is used and not the legacy /usr/bin/awk.

An other solution is to pass it as an argument and use the ARGV
special array in awk. There are other solutions using the -v
option of awk or the old var=value awk argument convention, or
have the shell expand the value of the variable within the awk
code argument, but none of them are suitable for a regexp as
$criteria is as they won't work if special characters are
present in the variable (and those special characters are often
found in regexps). 

-- 
Stephane

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