UNIX for Dummies Questions & Answers

Since I found this very helpful forum and friendly people, I have a small request.

I use AIX Unix and would like to know if there's a simple way how to do a kind of compare between two files. Should I use some grep, find or awk?

I have 2 text files, let's name them file1 and file2.

What I need:

I want to read line by line file1 - certain field or better 2 fields of the file1 and look up the information in the file2.

To be more descriptive: I'd like to extract field1 at position 10-15 and field2 at position 25-31 from file1 and search or find if the same information is somewhere inside the file2. When no, I'd like to output the field1 & field2 off the file1 doesn't exit in file2.

let's say file1 contains something like:

123232 3232 2323 2323123123213 trterert

and file2 e.g.

123232 3232 2323 2323123123213 XXXXXXXX

and let's say I want 123232 & trterert from file1 to be searched in file2 ==> I get an "error" because the script would find only 123232 and not trterert.....

I'd be more than happy if someone can help me out or recommend a link or appropriate command or script.

I just need to check some record(s) in one file - and if they're available in the other file...

Please! Thanks.

recent thread example

Many thanks, going to look at it.

tried the examples in the thread - not working

any suggestions?

So do I understand this correctly: if there is a line in file2 which does not contain both the information in columns 10-15 in file1, and the information in columns 20-25 in file1, then you want to print that line from file2, and additionally, any lines from file1 which did not have any such matches in file2?

Do the matches have to be from the same line in file1, or would, say columns 10-15 on line 1 and columns 20-25 on line 2 together constitute a match? (I'm guessing no, here.)

Can the matches be overlapping? Say you search for "12345" and "23456", then can the single value "123456" be considered a match on both of these fields at the same time? (I'm guessing this is okay, or doesn't matter in practice.)

Your examples don't match. Columns 10-15 in your file1 don't contain "123232" and columns 25-31 don't contain "treret". Can you come up with a correct example?

Code:

while read line; do
  grep "`echo "$line" | cut -c10-15`" file2 | grep "`echo "$line" | cut -c25-31`" || echo "$line" >&2
done <file1 | fgrep -vxf - file2

This will print non-matches from file1 to standard error and non-matches from file2 to standard output.

Using echo in backticks is always somewhat fragile if the values have significant leading or trailing whitespace. If the values you seek will not contain whitespace, this might even work, but it's hard to test without real-world samples.