String module

Overview

The string module provides comprehensive string manipulation utilities in pure Bash. All functions avoid external tools where possible, making them fast and portable. Total functions: 130+

Inspection

Functions for checking string properties and contents.

string::length

Returns the length of a string.

string::length "hello world"
# Output: 11

Parameters:

str - The string to measure

Returns: Integer length

string::is_empty

Check if a string is empty.

if string::is_empty ""; then
  echo "String is empty"
fi

Returns: Exit code 0 if empty, 1 otherwise

string::is_not_empty

Check if a string is non-empty.

if string::is_not_empty "hello"; then
  echo "String has content"
fi

Returns: Exit code 0 if non-empty, 1 otherwise

string::contains

Check if string contains a substring.

if string::contains "hello world" "world"; then
  echo "Found!"
fi

Parameters:

haystack - The string to search in
needle - The substring to find

Returns: Exit code 0 if found, 1 otherwise

string::starts_with

Check if string starts with a prefix.

string::starts_with "hello world" "hello"
# Returns: 0 (true)

Parameters:

str - The string to check
prefix - The prefix to match

string::ends_with

Check if string ends with a suffix.

string::ends_with "hello.txt" ".txt"
# Returns: 0 (true)

Parameters:

str - The string to check
suffix - The suffix to match

string::matches

Check if string matches a regex pattern.

string::matches "hello123" "^[a-z]+[0-9]+$"
# Returns: 0 (true)

Parameters:

str - The string to test
regex - Bash-compatible regex pattern

Validation functions

string::is_integer

Check if string is a valid integer (including negative).

string::is_integer "-42"  # true
string::is_integer "3.14" # false

string::is_float

Check if string is a valid float (supports scientific notation).

string::is_float "3.14"    # true
string::is_float "1.5e-10" # true

string::is_hex

Check if string is hexadecimal (with or without 0x prefix).

string::is_hex "0xFF"  # true
string::is_hex "DEADBEEF" # true

string::is_bin

Check if string is binary (0b prefix required).

string::is_bin "0b1010" # true

string::is_octal

Check if string is octal (leading 0 required).

string::is_octal "0755" # true

string::is_numeric

Check if string is numeric in any format (int, float, hex, binary, octal).

string::is_numeric "42"     # true
string::is_numeric "0xFF"   # true
string::is_numeric "3.14"   # true

string::is_alnum

Check if string is alphanumeric only.

string::is_alnum "abc123" # true
string::is_alnum "abc-123" # false

string::is_alpha

Check if string is alphabetic only.

string::is_alpha "hello" # true
string::is_alpha "hello1" # false

Case conversion

Functions for changing string case.

string::upper

Convert string to uppercase.

string::upper "hello world"
# Output: HELLO WORLD

Use string::upper::legacy for Bash 3 compatibility (uses tr)

string::lower

Convert string to lowercase.

string::lower "HELLO WORLD"
# Output: hello world

Use string::lower::legacy for Bash 3 compatibility

string::capitalise

Capitalize first character only.

string::capitalise "hello world"
# Output: Hello world

Use string::capitalise::legacy for Bash 3 compatibility

string::title

Convert to title case (capitalize each word).

string::title "hello world from bash"
# Output: Hello World From Bash

Requires: awk

Naming convention conversion

Convert between different naming conventions: plain, snake_case, kebab-case, camelCase, PascalCase, CONSTANT_CASE, dot.case, and path/case.

From plain (space-separated)

string::plain_to_snake

string::plain_to_snake "hello world"
# Output: hello_world

string::plain_to_kebab

string::plain_to_kebab "hello world"
# Output: hello-world

string::plain_to_camel

string::plain_to_camel "hello world"
# Output: helloWorld

string::plain_to_pascal

string::plain_to_pascal "hello world"
# Output: HelloWorld

string::plain_to_constant

string::plain_to_constant "hello world"
# Output: HELLO_WORLD

string::plain_to_dot

string::plain_to_dot "hello world"
# Output: hello.world

string::plain_to_path

string::plain_to_path "hello world"
# Output: hello/world

From snake_case

string::snake_to_plain

string::snake_to_plain "hello_world"
# Output: hello world

string::snake_to_kebab

string::snake_to_kebab "hello_world"
# Output: hello-world

string::snake_to_camel

string::snake_to_camel "hello_world"
# Output: helloWorld

string::snake_to_pascal

string::snake_to_pascal "hello_world"
# Output: HelloWorld

string::snake_to_constant

string::snake_to_constant "hello_world"
# Output: HELLO_WORLD

string::snake_to_dot

string::snake_to_dot "hello_world"
# Output: hello.world

string::snake_to_path

string::snake_to_path "hello_world"
# Output: hello/world

From kebab-case

string::kebab_to_plain

Converts hello-world → hello world

string::kebab_to_snake

Converts hello-world → hello_world

string::kebab_to_camel

Converts hello-world → helloWorld

string::kebab_to_pascal

Converts hello-world → HelloWorld

string::kebab_to_constant

Converts hello-world → HELLO_WORLD

string::kebab_to_dot

Converts hello-world → hello.world

string::kebab_to_path

Converts hello-world → hello/world

From camelCase

string::camel_to_plain

Converts helloWorld → hello world

string::camel_to_snake

Converts helloWorld → hello_world

string::camel_to_kebab

Converts helloWorld → hello-world

string::camel_to_pascal

Converts helloWorld → HelloWorld

string::camel_to_constant

Converts helloWorld → HELLO_WORLD

string::camel_to_dot

Converts helloWorld → hello.world

string::camel_to_path

Converts helloWorld → hello/world

From PascalCase

string::pascal_to_plain

Converts HelloWorld → hello world

string::pascal_to_snake

Converts HelloWorld → hello_world

string::pascal_to_kebab

Converts HelloWorld → hello-world

string::pascal_to_camel

Converts HelloWorld → helloWorld

string::pascal_to_constant

Converts HelloWorld → HELLO_WORLD

string::pascal_to_dot

Converts HelloWorld → hello.world

string::pascal_to_path

Converts HelloWorld → hello/world

From CONSTANT_CASE

string::constant_to_plain

Converts HELLO_WORLD → hello world

string::constant_to_snake

Converts HELLO_WORLD → hello_world

string::constant_to_kebab

Converts HELLO_WORLD → hello-world

string::constant_to_camel

Converts HELLO_WORLD → helloWorld

string::constant_to_pascal

Converts HELLO_WORLD → HelloWorld

string::constant_to_dot

Converts HELLO_WORLD → hello.world

string::constant_to_path

Converts HELLO_WORLD → hello/world

From dot.case

string::dot_to_plain

Converts hello.world → hello world

string::dot_to_snake

Converts hello.world → hello_world

string::dot_to_kebab

Converts hello.world → hello-world

string::dot_to_camel

Converts hello.world → helloWorld

string::dot_to_pascal

Converts hello.world → HelloWorld

string::dot_to_constant

Converts hello.world → HELLO_WORLD

string::dot_to_path

Converts hello.world → hello/world

From path/case

string::path_to_plain

Converts hello/world → hello world

string::path_to_snake

Converts hello/world → hello_world

string::path_to_kebab

Converts hello/world → hello-world

string::path_to_camel

Converts hello/world → helloWorld

string::path_to_pascal

Converts hello/world → HelloWorld

string::path_to_constant

Converts hello/world → HELLO_WORLD

string::path_to_dot

Converts hello/world → hello.world

Trimming and whitespace

Functions for removing or normalizing whitespace.

string::trim_left

Remove leading whitespace.

string::trim_left "  hello"
# Output: hello

string::trim_right

Remove trailing whitespace.

string::trim_right "hello  "
# Output: hello

string::trim

Remove both leading and trailing whitespace.

string::trim "  hello world  "
# Output: hello world

string::collapse_spaces

Collapse multiple consecutive spaces into one.

string::collapse_spaces "hello    world"
# Output: hello world

Requires: tr

string::strip_spaces

Remove all whitespace from string.

string::strip_spaces "hello world"
# Output: helloworld

Substrings

Functions for extracting parts of strings.

string::substr

Extract substring starting at position.

string::substr "hello world" 6 5
# Output: world

string::substr "hello world" 6
# Output: world (to end)

Parameters:

str - Source string
start - Starting position (0-indexed)
length - Optional length to extract

string::index_of

Find index of first occurrence of substring.

string::index_of "hello world" "world"
# Output: 6

string::index_of "hello world" "xyz"
# Output: -1 (not found)

string::before

Return everything before first occurrence of delimiter.

string::before "[email protected]" "@"
# Output: user

string::after

Return everything after first occurrence of delimiter.

string::after "[email protected]" "@"
# Output: example.com

string::before_last

Return everything before last occurrence of delimiter.

string::before_last "path/to/file.txt" "/"
# Output: path/to

string::after_last

Return everything after last occurrence of delimiter.

string::after_last "path/to/file.txt" "/"
# Output: file.txt

Manipulation

Functions for modifying strings.

string::replace

Replace first occurrence of search string.

string::replace "hello world" "world" "bash"
# Output: hello bash

string::replace_all

Replace all occurrences of search string.

string::replace_all "foo bar foo" "foo" "baz"
# Output: baz bar baz

string::remove

Remove all occurrences of a substring.

string::remove "hello world" "l"
# Output: heo word

string::remove_first

Remove first occurrence of a substring.

string::remove_first "hello world" "l"
# Output: helo world

string::reverse

Reverse a string.

string::reverse "hello"
# Output: olleh

Requires: rev (falls back to awk)

string::repeat

Repeat a string n times.

string::repeat "*" 5
# Output: *****

string::pad_left

Pad string on the left to reach width.

string::pad_left "42" 5 "0"
# Output: 00042

string::pad_left "hi" 5
# Output:    hi (spaces by default)

Parameters:

str - String to pad
width - Target width
char - Padding character (default: space)

string::pad_right

Pad string on the right to reach width.

string::pad_right "hi" 5
# Output: hi   

string::pad_center

Center a string within given width.

string::pad_center "hello" 11
# Output:    hello   

string::truncate

Truncate string to max length with ellipsis.

string::truncate "hello world" 8
# Output: hello...

string::truncate "hello world" 5
# Output: he…

Parameters:

str - String to truncate
max - Maximum length (including suffix)

Behavior:

Uses ... for lengths > 5
Uses … (single ellipsis) for shorter lengths
Intelligently handles very small max values

Splitting and joining

string::split

Split string by delimiter into lines.

string::split "a,b,c" ","
# Output:
# a
# b
# c

Each element is printed on a separate line.

string::join

Join arguments with delimiter.

string::join "," "a" "b" "c"
# Output: a,b,c

Parameters:

delimiter - String to insert between elements
args... - Elements to join

Encoding and hashing

URL encoding

string::url_encode

URL-encode a string (percent-encoding).

string::url_encode "hello world!"
# Output: hello%20world%21

string::url_decode

Decode a URL-encoded string.

string::url_decode "hello%20world%21"
# Output: hello world!

Base64 encoding

string::base64_encode

Encode string as Base64 (uses system base64 command).

string::base64_encode "hello"
# Output: aGVsbG8=

Cross-platform (handles macOS and Linux differences).

string::base64_decode

Decode Base64 string.

string::base64_decode "aGVsbG8="
# Output: hello

string::base64_encode::pure

Pure Bash Base64 encoder (no external tools).

string::base64_encode::pure "hello"

string::base64_decode::pure

Pure Bash Base64 decoder.

string::base64_decode::pure "aGVsbG8="

Base32 encoding

string::base32_encode

Encode string as Base32.

string::base32_encode "hello"

Requires: base32 or gbase32 (GNU coreutils)

string::base32_decode

Decode Base32 string.Requires: base32 or gbase32

string::base32_encode::pure

Pure Bash Base32 encoder (no external tools).

string::base32_decode::pure

Pure Bash Base32 decoder.

Cryptographic hashes

string::md5

Compute MD5 hash of string.

string::md5 "hello"
# Output: 5d41402abc4b2a76b9719d911017c592

Requires: md5sum (Linux) or md5 (macOS)

MD5 is not cryptographically secure. Use for checksums only.

string::sha256

Compute SHA-256 hash of string.

string::sha256 "hello"
# Output: 2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824

Requires: sha256sum (Linux) or shasum (macOS)

Generation

Functions for generating random strings and identifiers.

string::random

Generate random alphanumeric string.

string::random 16
# Output: a7d9f2k4m8p1q3x5 (example)

Parameters:

length - Length of string to generate (default: 16)

Requires: /dev/urandom

string::uuid

Generate a UUID v4 (random).

string::uuid
# Output: 550e8400-e29b-41d4-a716-446655440000 (example)

Requires: uuidgen or /proc/sys/kernel/random/uuid (falls back to manual construction)

Text & Data

System & Runtime

User Interface

Utilities

External Tools

Overview

Inspection

Validation functions

Case conversion

Naming convention conversion

From plain (space-separated)

From snake_case

From kebab-case

From camelCase

From PascalCase

From CONSTANT_CASE

From dot.case

From path/case

Trimming and whitespace

Substrings

Manipulation

Splitting and joining

Encoding and hashing

URL encoding

Base64 encoding

Base32 encoding

Cryptographic hashes

Generation

Build docs developers (and LLMs) love

Text & Data

System & Runtime

User Interface

Utilities

External Tools

​Overview

​Inspection

​Validation functions

​Case conversion

​Naming convention conversion

​From plain (space-separated)

​From snake_case

​From kebab-case

​From camelCase

​From PascalCase

​From CONSTANT_CASE

​From dot.case

​From path/case

​Trimming and whitespace

​Substrings

​Manipulation

​Splitting and joining

​Encoding and hashing

​URL encoding

​Base64 encoding

​Base32 encoding

​Cryptographic hashes

​Generation

Build docs developers (and LLMs) love

Overview

Inspection

Validation functions

Case conversion

Naming convention conversion

From plain (space-separated)

From snake_case

From kebab-case

From camelCase

From PascalCase

From CONSTANT_CASE

From dot.case

From path/case

Trimming and whitespace

Substrings

Manipulation

Splitting and joining

Encoding and hashing

URL encoding

Base64 encoding

Base32 encoding

Cryptographic hashes

Generation