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Shell Programming and Scripting

Passing key column from parent to child records

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# 8  
Old 06-03-2016
if AM00 does not start in position 13 then I don't want to add any suffix to children records.
# 9  
Old 06-03-2016
Oh, I see - didn't jump to my eyes immediately.

If a "record separator" were a blank line, try e.g.
Code:
!NF {SUFFIX = ""};

to the begin of the one-liner.
# 10  
Old 06-03-2016
Thank you Rudy.

This is my code but it didn't quite work - suffix = 99 still showing up on the 2nd record:
Code:
awk '!NF {SUFFIX = ""}; substr($0,13,4)=="AM00" {SUFFIX = substr($0,38,2)} substr($0,13,4)=="AM01" {$0 = $0 FS SUFFIX} 1'  file

on a side note, is it possible to store substr($0,13,4) in a variable?

I tried this but it didn't work:
Code:
awk '!NF {SUFFIX = ""}; var1=substr($0,13,4) "$var1"=="AM00" {SUFFIX = substr($0,38,2)} substr($0,13,4)=="AM01" {$0 = $0 FS SUFFIX} 1'  file

# 11  
Old 06-03-2016
Is NF really zero (== EMPTY line, not even spaces in there)?

Assignment to a variable IS possible but should be done in an action part (i.e. within { and } )
# 12  
Old 06-03-2016
also...
"$var1"=="AM00" should be var1 == "AM00"
# 13  
Old 06-03-2016
This is my final code in an attempt to use variables:

Code:
awk 'rec_type1=substr($0,13,4) {$rec_type1=="AM00"} {SUFFIX = substr($0,38,2)} substr($0,13,4)=="AM01" {$0 = $0 FS SUFFIX} 1'  file

it's Not working as expected using variables

Code:
Input Data:
000000000001AM00 1500895700000000000100                                                                                     
000000000001AM01 035000000000013000399820810000000P 

Output Data:
000000000001AM00 1500895700000000000100                                                                                     
000000000001AM01 035000000000013000399820810000000P 98

it's grabbing SUFFIX = 98 for the current record, not from the previous one.

Please help.

Thank you.
# 14  
Old 06-03-2016
Please get accustomed to reading man awk!

awk works on pattern {action} pairs for every input record: execute action if pattern is TRUE.

Code:
awk '
rec_type1=substr($0,13,4)                       # assignment; wrong: usually an action
{$rec_type1=="AM00"}                            # comparison; wrong: should be used as a pattern or within an "if" construct; wrong: the $ in front of var
{SUFFIX = substr($0,38,2)}                      # action alone; executed for every record as missing pattern is assumed TRUE
substr($0,13,4)=="AM01" {$0 = $0 FS SUFFIX}     # correct pattern {action} pair!
1                                               # TRUE pattern; executes default action: print $0
'  file

This User Gave Thanks to RudiC For This Post:
pchang
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