🛤 Path filters

Path filters assume that their input value is a FS path.

Path components

Filter	Description	Filter	Description
d	Parent directory	D	Remove last name
f	File name	F	Last name
b	Base name	B	Remove extension
e	Extension	E	Extension with dot

For input value /home/alice/notes.txt, filters would evaluate to:

Pattern	Output
{}	/home/alice/notes.txt
{d}, {D}	/home/alice
{f}, {F}	notes.txt
{b}	notes
{B}	/home/alice/notes
{e}	txt
{E}	.txt

Parent directory d might give a different result than D which removes last name of a path. Similarly, file name f might not be the same as last name F which is a complement of D.

Input	{d}	{D}	{f}	{F}
/	/	/	(empty)	(empty)
/a	/	/	a	a
a/b	a	a	b	b
a	.	(empty)	a	a
.	./..	(empty)	(empty)	.
..	../..	(empty)	(empty)	..
(empty)	..	(empty)	(empty)	(empty)

Extension with dot E can be useful when dealing with files with no extension.

Input	new.{e}	new{E}
old.txt	new.txt	new.txt
old	new.	new

Absolute and relative paths

Filter	Description
w	Working directory
a	Absolute path
A	Relative path

Absolute path a and relative path A are both resolved against working directory w.

{w}	Input	{a}	{A}
/home/alice	/home/bob	/home/bob	../bob
/home/alice	../bob	/home/bob	../bob

By default, working directory w is set to your current working directory. You can change that using the -w, --working-directory option. w filter will always output an absolute path, even if you set a relative one using the -w option.

rew -w '/home/alice' '{w}' # Absolute path
rew -w '../alice'    '{w}' # Relative to your current working directory

Path normalization

Filter	Description
p	Normalized path
P	Canonical path

Normalized path p is constructed using the following rules:

• On Windows, all / separators are converted to \.
• Consecutive directory separators are collapsed into one.
• Non-root trailing directory separator is removed.
• Unnecessary current directory . components are removed.
• Parent directory .. components are resolved where possible.
• Initial .. components in an absolute path are dropped.
• Initial .. components in a relative path are kept.
• Empty path is resolved to . (current directory).

Input	Output	Input	Output
(empty)	.	/	/
.	.	/.	/
..	..	/..	/
a/	a	/a/	/a
a//	a	/a//	/a
a/.	a	/a/.	/a
a/..	.	/a/..	/
./a	a	/./a	/a
../a	../a	/../a	/a
a//b	a/b	/a//b	/a/b
a/./b	a/b	/a/./b	/a/b
a/../b	b	/a/../b	/b

Canonical path P works similarly to p but has some differences:

• Evaluation will fail for a non-existent path.
• Result will always be an absolute path.
• If path is a symbolic link, it will be resolved.

Directory separator

Filter	Description
z	Ensure trailing directory separator
Z	Remove trailing directory separator

Directory separator filters z and Z can be useful when dealing with root and unnormalized paths.

Input	{}b	{}/b	{z}b	{Z}/b
/	/b	//b	/b	/b
a	ab	a/b	a/b	a/b
a/	a/b	a//b	a/b	a/b