Shell Programming and Scripting

You can further shorten your script like this:

Code:

awk 'FILENAME=="target" {arr[$1]++}
     FILENAME=="lookup" && !($1 in arr) {print $0}' target lookup > out

and then:

Code:

awk 'FILENAME=="target" {arr[$1]++}
     FILENAME=="lookup" && !($1 in arr)' target lookup > out

I used $1 instead of $0 so that there are no mismatches due to spacing differences..

so just to read that back in my head

"if the value in $0 is not in the equiavalent array position, print said value"

where the exclamation mark represents the "not in" condition?

@#9 : indeed

interesting. how comes the former doesnt print on screen first despite the print $0?

having trouble reading back the red bit. what are we doing here?

It does not print on screen because of the redirect of stdout of awk to the file "out" (> out)
The red part makes use of the fact that {print $0} is the default action in awk so you can leave that out.

makes sense. enhancing it further to allow user to provide a path for the target file. was pretty simple and got that working.

Code:

echo 'enter full path to eodfeed file'
read targetpath
echo $targetpath
awk '
FILENAME=="$targetpath" {arr[$1]++}
FILENAME=="lookup" && !($1 in arr) ' $targetpath lookup > out

now id like to offer the user to provide the path of a file that itself contains multiple paths to target files. the script would then lookup against each target file in a loop and save the results to a separate output file (which would be conveniently named after the target file the lookup was carried against)

so the user would provide the location of a file that contains the following
/opt/ice/server/targetfile1
/opt/ice/server/targetfile2
/opt/ice/server/targetfile3

the script would use "lookup" file against each one of the above and output the results as
out_targetfile1
out_targetfile2
out_targetfile3

before i have a crack at it, im trying to figure out where id start
i guess the first thing is to read the file the user has provided and store the 3 locations into an array (this is within the awk). start a for loop, for each i in arr do <awk program that already works>

on the right tracks?

The code in #13 will not work IMO, since $targetpath does not get evaluated inside the ' '
But I think we can leave targetpath out entirely if we use a next statement:

Code:

awk ' FILENAME=="lookup" && !($1 in arr){print; next} {arr[$1]++} ' "$targetpath" lookup

Now using the user provided file that contains the target, I would get the targetfile from the user and then I would just use this code in a while-read loop in the shell :

Code:

while read file
do
   if [ -r "$file" ]; then
     awk ' FILENAME=="lookup" && !($1 in arr){print; next} {arr[$1]++} ' "$file" lookup > "$file.out"
   fi
done < "$targetfile"