Pattern Matching (Globbing) in Bash¶

Pattern matching, or globbing, is a way to match files and directories.

Relevant shell options:

globstar
extglob

Quickref¶

Pattern Matching Characters:¶

Character	Meaning
`*`	Zero or more characters (any characters)
`?`	One or more characters (any characters)
`[a-z]`	Match a range of characters.
`'[:lower:]'`	Match a class of characters.
`[^a-z]`	Negate a range (match anything except the range).
`[Rr]`	Match one occurence of `r` or `R`

This is the only way to do matching in certain types of shell interpreters.

Extended Pattern Matching Operators¶

Note: This requires the extglob option to be enabled with shopt -s extglob. When extended pattern matching becomes available, you have access to more types of operators.

In the following table, a pattern-list is a list of one or more patterns separated by a |.

Operator	Description
`?(pattern-list)`	Matches zero or one occurrence of the given patterns
`*(pattern-list)`	Matches zero or more occurrences of the given patterns
`+(pattern-list)`	Matches one or more occurrences of the given patterns
`@(pattern-list)`	Matches one of the given patterns
`!(pattern-list)`	Matches anything except one of the given patterns

Character Classes in Sets¶

Inside a set ([ ]), character classes can be specified using [:class:] Class is one of the classes defined in the POSIX standard:

Character Class	Description
`[:alnum:]`	Alphanumeric characters (letters and digits).
`[:alpha:]`	Alphabetic characters (letters only).
`[:ascii:]`	ASCII characters (characters in the ASCII character set).
`[:blank:]`	Blank characters (space and tab).
`[:cntrl:]`	Control characters (non-printing characters).
`[:digit:]`	Digits (0-9).
`[:graph:]`	Graphical characters (characters that are visible, not space).
`[:lower:]`	Lowercase letters.
`[:print:]`	Printable characters (graphical characters plus space).
`[:punct:]`	Punctuation (characters not in `[:alnum:]`, `[:cntrl:]`, or `[:space:]`).
`[:space:]`	Whitespace characters (space, tab, newline, etc.).
`[:upper:]`	Uppercase letters.
`[:word:]`	Word characters (alphanumeric characters plus underscore).
`[:xdigit:]`	Hexadecimal digits (0-9, A-F, a-f).

All character classes above are availbe in Vim, in addition to:

Character Class	Description
`[:tab:]`	The `<Tab>` character
`[:escape:]`	The `<Esc>` character
`[:backspace:]`	The `<BS>` character
`[:ident:]`	Identifier character (same as `\i`)
`[:keyword:]`	Keyword character (same as `\k`)
`[:fname:]`	File name character (same as `\f`)

Ranges in Sets¶

Ranges of characters can also be specified inside sets, using the syntax [x-y]. [a-Z] is a set of characters, their numeric equivalent is what will be compared.

If the first character following the opening bracket [ is a ! or a ^ then any character not enclosed is matched. E.g.,

[!a-z]
[^a-z]

Those two patterns will match any character not in the range a-z.

Recursively find all files in a directory¶

`**` in patterns with `globstar`:¶

When the globstar shell option is enabled, and two *s (**) are used as a single pattern in a pathname expansion, it'll match all files recursively, and zero or more directories and subdirectories.

Use globstar to find all files in a directory:

**/*.c   # all C files in the current directory and subdirectories
**/*.go  # all Go files in the current directory and subdirectories
**/*     # all files in the current directory and subdirectories

git commit -m "feat: Add directory for android notes"