notIn.md

Motivation

https://github.com/c-blake/ndup has a POSIX shell script, sh/ndup which keeps a mirrored set of files related to some source files. A natural course of file management (especially with duplicate/near duplicate removal in play) is the user creating new files or directories, renaming old ones, etc. With any sort of mirrored hierarchy of derived files, this induces a need to clean up stale derivations. This is what notIn helps do.

The salient line in the above mentioned script is:

notIn -f$w/f0 $w/digs $w/sets | xargs -0 rm -fv

This will remove any files under digs/ or sets/ that are not in the path list file f0 (hence the program name notIn).

I have not used it for this personally, but another example use case might be a parallel hierarchy used for lc -X,--extra extra parameter values for lc only just where a user has permission to write. In this case, due to the nature of lc, you probably only care about stale directories.

In general, parallel file trees can be an interesting tool both conceptually and practically and notIn can help to maintain them/query disparities/etc.

Usage

  notIn [optional-params] [roots: string...]

Find files under roots NOT matching pattern applied to any file entry.  E.g.:
  (cd D1; find . -print0) | notIn D2 D3 | xargs -0 echo
echoes every entry under D2 or D3 not also under D1.

Input paths are normalized to nix empty parts (e.g. 1st&3rd in "./foo/./bar").

find -path A -o -path B .. can do this, but is hard for many paths.

  -f=, --file=    string ""     delimited input ( "" => stdin )
  -d=, --delim=   char   '\x00' input path delimiter
  -t=, --term=    char   '\x00' output path terminator
  -p=, --pattern= string "$1"   a $1-containing under roots pattern
  -v, --invert    bool   false  find files that do match a file entry