Shell Programming and Scripting

If that is an issue then try:

Code:

cut -c 1-25 source.list > source.temp && grep -vxFf source.temp complete.list > missing.list; [ -e source.temp ] && rm -f source.temp

---------- Post updated at 09:30 PM ---------- Previous update was at 08:49 PM ----------

I wonder if this will produce the same result you are looking for:

Code:

awk -F"@" 'NR==FNR {a[$1];next} {if($1 in a){next;}print $1}' incomplete.list source.list

Thanks a lot!!

Yep this awk -F"@" 'NR==FNR {a[$1];next} {if($1 in a){next;}print $1}' source.list complete.list works! And it is so flexible and thus the difference could be done both ways. Thank you so much.

The temp file removal also works. Thanks.

So, could you explain both of the codes? What does the [ -e source.temp ] acts for?

Thanks again.

If was possible to just do:

Code:

cut -c 1-25 source.list > source.temp && grep -vxFf source.temp complete.list > missing.list; rm -f source.temp

which will try to delete source.temp regardless of any other previous command, however, that would display an error if it was not found.

[ -e source.temp ] (notice the spaces after [ and before ], very important) is test. (take a look at man test), -e evaluates to true if exists, so if that is true then continue to rm -f, avoiding the error message.

Awk

-F"@" make the field separator an `@', that takes care of the format of source.list, dividing each line into two fields, before the `@' and after the `@'

NR==FNR {a[$1];next} this part is only for the first file, in this case source.list. The build-in variable NR is set to the total number of records found from all files, the build-in variable FNR is only the number of records in the current reading file, so as long as both are the same, we are reading only from the first file, if so perform the instructions on the first set of {a[$1];next} which only keeps an array named `a[name of the field]' and skip the rest of the instructions.

Now, we have the whole first file indexed in memory.

{if($1 in a){next;}print $1}'The rest is just an evaluation for the second file, if any of the records are seen already, do nothing (skip to next), otherwise, display it because is missing.

Thanks a lot @Aia

So in conclusion, there is no way for me to mimic the process substitution by any other means right?

Because...

Code:

$ ls /dev/fd
/dev/fd not found

Thanks a lot to all.

Well, there might be. Try

Code:

cut -c 1-25 source.list | grep -vxFf - complete.list

The -f - will use stdin as the pattern file.

Maybe my suggestion is outside your main concern on temp files, but you can also try this.
Both input files should be sorted

Code:

$ join -t\@  -v1  incomplete.list source.list

join is a very powerfull tool that helps you process files as databases , provide they are sorted.