bash scripting - case statement not evaluating string (values) correctly

Question

I need help figuring out why my case statement is not properly evaluating my first 2 values (visitor_id, updated) in my list. Here's the code:

#!/usr/local/bin/bash
file="mydatasample.out";
linecount=$(wc -l <"$file" | awk '{ print $1 }')
counter=1
while IFS='' read -r column; do
  case column in
    visitor_id)
       echo "isnull($column|| '[|]' ||";;
       updated)
       echo "isnull($column::text || '[|]' ||";;
             *)
       echo "isnull($column::text,'[null!]') || '[|]' ||";;
  esac
  if [ "$counter" -eq "$linecount" ]; then
      echo "isnull($column::text,'[null!]')) as md5sum"
  fi
  ((counter++))
done <"$file"

=mydatasample.out=

visitor_id
updated
visitor_1_key
visitor_1_value
visitor_2_key
visitor_2_value

Getting:

isnull(visitor_id::text,'[null!]') || '[|]' ||
isnull(updated::text,'[null!]') || '[|]' ||
isnull(visitor_1_key::text,'[null!]') || '[|]' ||
isnull(visitor_1_value::text,'[null!]') || '[|]' ||
isnull(visitor_2_key::text,'[null!]') || '[|]' ||
isnull(visitor_2_value::text,'[null!]')) as md5sum

Expecting:

isnull(visitor_id|| '[|]' ||
isnull(updated::::text || '[|]' ||
isnull(visitor_1_key::text,'[null!]') || '[|]' ||
isnull(visitor_1_value::text,'[null!]') || '[|]' ||
isnull(visitor_2_key::text,'[null!]') || '[|]' ||
isnull(visitor_2_value::text,'[null!]')) as md5sum

So, its the first (2) values that I want to evaluate, but so far cannot. Thanks for your help.

shellcheck autodetects this and other common problems. You can consider installing it in your editor. — that other guy
– that other guy, Commented Jan 26, 2018 at 21:14
Another suggestion: rather than all the linecount and counter stuff, just put the echo "... as md5sum" command after the loop, so it runs with the last value of $column. — Gordon Davisson
– Gordon Davisson, Commented Jan 27, 2018 at 6:00
@noober: Actually, I take it back; that wouldn't work. read sets column to each line as it's read, but after the last line there's a final read that reads the end-of-file and sets column to null. But if you add lastcolumn=$column inside the loop, then after the loop that'll have the last actual column left in the column variable, and you can use that to print the "... as md5sum". — Gordon Davisson
– Gordon Davisson, Commented Jan 30, 2018 at 22:02

choroba · Accepted Answer · 2018-01-26 21:12:00Z

3

case, unlike for, doesn't interpret column as $column (because for needs to know the name of the variable to assign to, while case needs to know the value to compare it).

You probably wanted

case "$column" in

edited Jan 26, 2018 at 21:12

answered Jan 26, 2018 at 21:09

choroba

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1 Comment

noober Over a year ago

yay! thank you very much. quick fix for sure. appreciate the help!

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