topic "if" processing in "awk". in Operating System - Linux

"if" processing in "awk".

Stuart Abramson — Tue, 23 Aug 2005 08:40:43 GMT

I have an "awk" program, in which I can't get the "if" conditions to work:

syminq -sym -v | awk '
/Device Phys/ {DEV=substr($5,11); next}
/Product ID/ {PROD=substr($4,1,4); next}
/Capacity/ {CAP=$5; next}
/12-digit Symm/ {ARRAY=substr($5,9); next}
/Device Symm/ {LUN=$5; next}
/ Device Ty/ {DEVTYP=substr($4,1,3); next} # BCV or REG
/Volume Logix/ {VCM=$5; next}
/Meta/ {META=$4; next}
/VxVM/ {CLRID=substr(ARRAY,3)
TYP=REG
if (META != "N/A") TYP=META
if (DEVTYP = "BCV") TYP=BCV
if (VCM = "YES") TYP="VCM"
print CLRID LUN "000", ARRAY, TYP, DEV, CAP}' \
| sort

I just always get "TYP is equal to "VCM", which it's not. Can someone tell me what I'm doing wrong?

Re: "if" processing in "awk".

Greg Vaidman — Tue, 23 Aug 2005 08:52:42 GMT

In your if statements, you want to use "==" and not "=". What you're doing is actually assigning the value rather than testing it, and the return code of an assignment is usually true, so that's why it's working that way.

--Greg

Re: "if" processing in "awk".

Rodney Hills — Tue, 23 Aug 2005 08:56:53 GMT

Don't use "=" to compare, use "==". A single "=" is an assignment which will return true in all your if statements.

HTH

-- Rod Hills

Re: "if" processing in "awk".

Pat Lieberg — Tue, 23 Aug 2005 08:59:32 GMT

Your syntax looks ok to me. It looks like you are testing three different variables to set TYP. The way its written, each of those if statements will be evaluated in sequence and every time one of them evaluates as true, the value of TYP is overwritten. The VCM statement being last might be why you always get that as the result.

Did you mean to use an "else if" statement? You would use that if one of the types is the default and you only want to deviate if certain conditions are true. For example, the code below sets TYP to META unless the if or the else if statement evaluate to true.

if (DEVTYP = "BCV") TYP=BCV
else if (VCM = "YES") TYP="VCM"
else (META != "N/A") TYP=META

Re: "if" processing in "awk".

Pat Lieberg — Tue, 23 Aug 2005 09:00:54 GMT

Ha! That's what I get for not looking close enough and for typing slow. Your syntax was wrong. Greg and Rodney both are right, you need to use ==.

Re: "if" processing in "awk".

Hein van den Heuvel — Tue, 23 Aug 2005 09:24:18 GMT

Those == for testing, and a bunch more quotes are needed:

TYP="REG";
if (META != "N/A") TYP="META"
if (DEVTYP == "BCV") TYP="BCV"
if (VCM == "YES") TYP="VCM"

Hein.

Re: "if" processing in "awk".

Stuart Abramson — Wed, 24 Aug 2005 08:03:58 GMT

Thanks all. "=="...