Nym is a cross-platform library and command line tool for manipulating files
using patterns. It is inspired by and very loosely based upon mmv.
Nym commands are formed from flags, options, and an actuator followed by a
transform comprised of a from-pattern and to-pattern. An actuator is a file
operation like append, copy, link, or move. A transform is a
from-pattern used to match source files and a to-pattern used to resolve
destination paths.
The following command copies all files in the working directory tree to a
neighboring file with an appended .bak extension:
shell
nym copy '**' '{#1}.bak'
Here, copy is the actuator, ** is the from-pattern, and {#1}.bak is the
to-pattern. In most shells, patterns must be escaped to avoid interacting with
features like expansion. Quoting patterns usually prevents these unwanted
interactions.
From-patterns match source files to actuate using Unix-like globs. Globs must
use / as a path separator. Separators are normalized across platforms; glob
patterns can match paths on Windows, for example.
Globs resemble literal paths, but support three wildcards: the tree wildcard
**, the zero-or-more wildcard *, and the exactly-one wildcard ?.
The tree wildcard ** matches zero or more sub-directories. This is the only
way to match against arbitrary directories; all other wildcards do not match
across directory boundaries. When a tree wildcard participates in a match and
does not terminate the pattern, its capture includes a trailing path separator.
If a tree wildcard does not participate in a match, its capture is an empty
string with no path separator. Tree wildcards must be delimeted by path
separators (or nothing, such as the beginning and/or end of a pattern).
The zero-or-more wildcard * matches zero or more of any character except
path separators. Zero-or-more wildcards cannot be adjacent to other
zero-or-more wildcards.
The exactly-one wildcard ? matches any single character except path
separators. Exactly-one wildcards do not group, so a pattern of contiguous
wildcards such as ??? form distinct captures for each ? wildcard.
To-patterns resolve destination paths. These patterns consist of literals,
captures from a corresponding from-pattern, and file properties. Non-literals
occur within curly braces {...}.
Captures are typically indexed from a from-pattern using a hash followed by an
index, like {#1}. These indices count from one; the zero index is used for the
full text of a match. Empty braces also respresent the full text of a match, so
{#0} and {} are equivalent.
Captures can also be named when the from-pattern is a raw binary regular
expression. Captures are referenced by name using @ followed by the name of
the desired capture, such as {@extension}. Note that named captures also have
a numerical index.
Captures may include a substitution. Substitutions specify a prefix and postfix that are inserted around the matching text when the capture is non-empty. Substitutions also specify alternative text, which is used if the capture is empty. This is useful when a pattern may not be present and an explicit replacement or optional delimeter is desired in the destination path.
Substitutions follow capture identifiers beginning with a question mark ? and
followed by a prefix, a postfix, and an alternative separated by colons :. For
example, {#1?:-:} is replaced by the matching text of the first capture and a
postfixed - if the capture is non-empty and is replaced with an empty string
otherwise. {#1?::unknown} is replaced by unknown if the capture is empty.
Properties include source file metadata in the destination path and are
specified following an exclamation !. Properties are case insensitive.
Supported properties are described in the following table.
| Pattern | Metadata |
|------------|----------------------------------------|
| {!b3sum} | [Blake3] hash of the source file. |
| {!ts} | Modified timestamp of the source file. |
Nym is loosely based upon mmv. Below are some initial ideas that have not yet
been implemented (in no particular order).
Install Rust and use cargo to install from a clone of the
repository.
shell
git clone https://github.com/olson-sean-k/nym.git
cd nym
cargo install --locked --path=. --force
Nym is offered as is with no warranty. At the time of writing, Nym is highly experimental and likely has many bugs. Data loss may occur. Use at your own risk.