CODEWITHSUNDEEP
shellvariablesawk
Melodie Gauthier
Melodie Gauthier

Reputation: 715

awk -v returns error

I need to keep only the 4 most recent file in a directory. I used the following command:

rm -f `ls -t $SOMEDIR/archive/* | awk 'NR>4'`

That's working. I'd like to use a variable NUM_TO_KEEP instead of the '4', so I tried the following:

NUM_TO_KEEP=4
rm -f `ls -t $SOMEDIR/archive/* | awk -v num=$NUM_TO_KEEP 'NR>$num'`

And I get the following error: awk: syntax error near line 1 awk: bailing out near line 1

I also tried a simple ls | awk -v var="foo" 'NR>4'

And I get the same error. I am trying this on linux and solaris and get the same error for both OS. Any idea on what I'm doing wrong? My question is regarding the error I get while using the '-v' option, as soon as I set a variable next to the -v option I get an error. (ls | awk -v 'NR>4' works, ls | awk -v="foo" 'NR>4' gives an error)

Upvotes: 0

Views: 321

Answers (1)

Ed Morton
Ed Morton

Reputation: 203985

Although this has been referred to as a dup and those other similar questions do solve part of your problem (how to access a shell variables value in an awk script), the real reason you are getting the specific error message awk: syntax error near line 1 awk: bailing out near line 1 is that you are using old, broken awk (usr/bin/awk on Solaris) which produces that error message for most awk scripts, valid or otherwise. Use GNU awk if at all possible, otherwise on Solaris use /usr/xpg4/bin/awk (or nawk but it is less POSIX-compatible).

Absolutely no-one should be using old, broken awk, so do not restrict your code based on assuming someone might be using it. If they are then they need to update their PATH to not do that. I'm extremely surprised you found a version of it on linux, I thought only Solaris had it malingering around. If you are writing a shell script you can just make sure to skip over it in the PATH before awk is called, e.g. pseudo-code:

if (I'm on Solaris)
then
    AWK=/usr/xpg4/bin/awk
else
    AWK=$(which awk)
fi
$AWK -v x=y 'script' file

or:

if [ ! awk -v x=y '1' /dev/null >/dev/null 2>&1 ]
then
    AWK=$(which awk | tail -1)
else
    AWK=$(which awk)
fi
$AWK -v x=y 'script' file

or something else that tests for the first awk in your PATH being old, broken awk and if so skips it to a different awk

Upvotes: 3

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