The style, the code, etc.

[ashevche]

It seems like the script doesn't keep a single style, has a lot of redundancy, etc.
E.g.,

if [ ! -d "$FOO" ]; then
  mkdir -p "$FOO"
fi

First of all this can be written as

[ -d "$FOO" ] || mkdir -p "$FOO"

but hey, the -p is exactly to avoid this all, and hence

mkdir -p "$FOO"

is enough.

Next one, cat ... | grep. Google for "useless use of cat", it is a very old idiom in UNIX to avoid unnecessary forks of processes that are not needed at all.

Last, but not least, change shebang to #!/bin/sh -efu and fix all issues with the script. It will get more portability and robustness.