File System Tools

Felix provides a number of tools to aid with portable file system operations. The primary driving concept behind these tools is that of a flat space of structured filenames which subsets of which can be identified by regular expressions.

The standard for regular expression is Google RE2.

All tools use unix standard pathname conventions in regular expressions. So / is the correct separator to use, even on Windows.

All tools use native conventions for directory names.

flx_ls

The simplest tool, flx_ls takes up to two arguments. The first argument is a directory name, the second a regular expression. It searches the directory and all subdirectories thereof recursively for pathnames exactly matching the regular expression, relative to the directory, and prints those that match, one per line, with names relative to the directory.

If the regular expression is omitted, .* is assumed, this matches all files. If the directory is omitted, ., the current directory is assumed.

Given the following directory structure:

Here are some examples:

>flx_ls top
leafA
leafB
nodeX/leafA
nodeX/leafC

>flx_ls top '.*leafA'
leafA
nodeX/leafA

>flx_ls top '.*/.*'
nodeX/leafA
nodeX/leafC

When using bash we strongly recommend enclosing the regexp in single quotes to ensure the regexp is treated as a single word and not interpreted.

Remember, the regexp must the pathname completely, from the first to last character inclusive.

This formulation for finding sets of files is much better than the common glob however you must remember that * means zero or more occurrences, and that . means any character. To find all files with an extension of three characters you would use:

>flx_ls top '.*\.[^.]{3}'

See: https://github.com/google/re2/wiki/Syntax for details.