Are you writing a perl script to do this because you don't have unix tools like "grep"? (There's no good reason why you should lack those tools.) 
# shell command, assuming there are not tons of files in file_path:

grep -h ^CQA_STATUS file_path/cqa_* > file_path/CQA_STATUS


# but if there are tons of files, do it like this:

find file_path -name 'cqa_*' | xargs grep -h ^CQA_STATUS > file_path/C
+QA_STATUS

# (update: added carets where needed)

[download]
Now, if these files had two or more lines starting with CQA_STATUS, and you only wanted to extract one of those lines, then you'd probably want a perl script -- and yes, you would want to go ahead and open each file in turn, and use perl's grep function (and/or whatever else is necessary to pick the particular line you want) in order to extract the target line from each file. Something like: 
open( O, ">", "file_path/CQA_STATUS" ) or die "CQA_STATUS: $!";

for my $file ( <file_path/cqa_*> )
{
    open( I, "<", $file ) or do { warn "$file: $!"; next };

    while (<I>) { # suppose we only want the first occurrence from eac
+h file
        if ( /^CQA_STATUS/ ) {
            print O;
            last;
        }
    }
    close I;
}
close O;

[download]

In reply to Re: extract a single line from multiple files in a folder. by graff
in thread extract a single line from multiple files in a folder. by august3

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