explainshell.com - rgrep.1 -lRE %27errorutil%5C.Handler%27 %7C xargs sed -i -E %27s%2FHandler%5C%28%28%5BA-Za-z0-9_%5C.%5D%2B%29%5C%29%2FHandler%28%5C1%2C %22default value%22%29%2F%27

-lRE %27errorutil%5C.Handler%27 %7C xargs sed -i -E %27s%2FHandler%5C%28%28%5BA-Za-z0-9_%5C.%5D%2B%29%5C%29%2FHandler%28%5C1%2C %22default value%22%29%2F%27

print lines matching a pattern

-l, --files-with-matches
       Suppress normal output; instead print the name of each input file from which output would normally
       have been printed.  The scanning will stop on the first match.  (-l is specified by POSIX.)

    -R, -r, --recursive
           Read all files under each directory, recursively; this is equivalent to the -d recurse option.

Other Options
    --line-buffered
           Use line buffering on output.  This can cause a performance penalty.

-i, --ignore-case
       Ignore case distinctions in both the PATTERN and the input files.  (-i is specified by POSIX.)