Can logical operators be used with find and xargs?

Question

I have a directory of about 5000 files of which some were erroneously written with a syntax error. I am using the following code to identify which files have the error:

ls -1 | while read a; do grep -q '^- ' $a || echo $a; done

I initially tried to use a combination of find and xargs but I couldn't figure out how to add the boolean logic I needed.

My use case is not I/O bound and completes fast enough. But I was curious to see if this same operation be done without relying on a bash loop. Although comfortable with Bash, I have a tendency to rely heavily on piping into loops which often leads to mind numbingly slow performance.

Answer 1

You can use boolean logic with find:

find -maxdepth 1 -type f \( -exec grep -q '^- ' {} \; -o -print \)

The -o option is a logical OR. If the command executed by -exec will return a non-zero return value -print will print the filename.

Answer 2

Here is another way to do this, using grep -L:

find -maxdepth 1 -type f -exec grep -L '^- ' {} \;

The code above would list all files on the directory which do NOT contain a line starting with dash + space - in their contents.

To make the code above recursive (that is, to extend the search to all subdirectories), just remove the -maxdepth 1 part out.

From man grep about option -L:

-L, --files-without-match Suppress normal output; instead print the name of each input file from which no output would normally have been printed. The scanning will stop on the first match.