Documentation

• What is nora?
• How to install
• Usage
• Example usage

What is Nora?

Nora is a command line utility for renaming files in batch using regex with advanced control. It is using a custom language created only for this purpose. Any suggestion is appricated (using github issues)

How to install

Comming soon

Usage

Command line usage

nora [OPTIONS] <INPUT> <OUTPUT>

Options

Input

Input is a regex expression. Capture groups can be used (see here for using them in the output)

Named Captrure groups also works (see here for using them in the output)

Output

The output expression is a little language easy to use

Two concepts are important, the unvariable parts and the interpreted parts

The unvariable part won't change when renaming while anything in the interpreted blocks will be interpreted considering this example:

[#1].txt

The unvariable part is the .txt An interpreted block starts with [ and ends with ] in this case the interpreted block is [#1] which contains #1

The interpreted block can have the following expressions

• Ternary expression
• Math expression
• String operation
• Identifiers
• String conversion
• Number conversion

Ternary expression

Example:

[#1 == 10 ? 1 : 2]

Dependant on the condition, if it's true 1 will be returned otherwise 2 will be returned

The condition operator can be any of these ==, !=, <, <=, >, >=

Ternary second parameter skip

If you you want to do a ternary as a normal if statement to write something if it's true but nothing if not Example:

[#1 == 10 ? "something" : ""]

The skip operator can be used to simplify this Example:

[#1 == 10 ?> "something"]

Math expression

Example:

[10 + 20]

currently supported operations are +, -, *, /, **, //, (, )

**: Power opertaor //: Log operator

It is important to note that math expressions will only be interpreted as mathematical expressions when the left paramter is a number (like JavaScript would)

For example:

["10" + 20]

This will give 1020 since it will convert the left to a string and do a concatenation

[10 + "20"]

This will give 30 since the left is a number and it will convert to string to a number automatically

String operation

Concatenation

Example:

["hello " + "world"]

It is important to note that concatenation of strings will only occur when the left paramter is a string (like JavaScript would)

For example:

["10" + 20]

This will give 1020 since it will convert the left to a string and do a concatenation

[10 + "20"]

This will give 30 since the left is a number and it will convert to string to a number automatically

Subtraction

Example:

["testes" - "te"]

This will give the ouput stes which removes the first te found

Multiple Subtraction

Example:

["testes" -- "te"]

This will give the ouput ss which removes all te found

Identifiers

Identifers are variables from the interpreter and the regex Example:

[#1]
[foo]
[bar]
[#count]

These are all variables variables starting with # are reserved for the interpreted (this means your capture groups shouldn't start with #)

Using capture groups

when using a regex, the capture groups can be used in interpreted block like the following

[#0]
[#1]
...
[#n]

The number represent the capture groups in order.

it is important to note that #0 the whole regex capture so the first capture group is #1

Using named capture groups

Using the named capture groups is similar to the normal capture group. The only difference is to ommit the # at the start

For example, if a named capture group is test it will be used as follows

[test]

Import Note: When using any capture group or named capture group identifiers, they are all strings by default.

To use mathematical expression when they are the left parameter of tha math epxression it is nessecary to convert them to numbers

String conversion

Example:

[string(#1)]

Transform the expression between the parenthese to a string

Number conversion

Example:

[number(#1)]

Transform the expression between the parenthese to a number

Example Usage

Rename files from (number).txt to (number).mkv

nora '(\d+)\..*' '[#1].mkv'

Rename files from (number).txt to (number + 10).txt

nora '(\d+)\..*' '[number(#1) + 10].txt'

Rename files from (number>.txt to (number + 10).txt only if (number) is 0 if not leave it as (number).txt

nora '(\d+)\..*' '[#1 == 0 ? number(#1) + 10 : #1].txt'