ls Command – Understanding the First Line of ls Output

I would guess that you have /home/sawa/foo/bar/ on your path - i.e. a path with a trailing slash.

which is iterating over each element of $PATH and appending /argv[1] and checking for the existence of that file. That causes a double-slash - one from the $PATH part, and one from /argv[1].

A double-slash is no problem. It is collapsed to a single slash by the kernel. Only at the beginning of a path may a double-slash have special meaning, and not always then.

As for test not working, ensure you are not using the shell built-in when calling test. You usually do this by using a full path, but with bash you can also use enable -n test to disable the built-in test command.

For question 1, you can do this:

find . -name "*.txt" | xargs grep -i "abc" | wc -l

This counts the total number of matches for abc in all text files.

And for question 2, I came up with:

find . -name "*.txt" -exec grep -i "abc" {} + | cut -d: -f1 | sort | uniq | wc -l

This gets just the unique filenames from the list of matches and counts them (the sort is probably not needed).

As pointed out by miracle173, grep comes with a "one match per file" flag so the command can be shortened to just:

find . -name "*.txt" -exec grep -il "abc" {} + | wc -l