Unlock Bash Mastery with the Pure Bash Bible Cheat Sheet

Introduction

Shell scripting is a core skill for Linux developers and operators. Using only Bash built‑ins enables quick, dependency‑free solutions for common tasks.

Why Write Scripts?

Scripts automate repetitive work, improve productivity, and require minimal learning time.

Why Use Bash Built‑ins?

Relying on built‑ins avoids external dependencies, making scripts portable and often more efficient.

Pure Bash Bible Repository

GitHub project: https://github.com/dylanaraps/pure-bash-bible (≈20 k stars). It catalogs common tasks achievable with Bash built‑ins only.

Key Topics Covered

String Operations

Trim leading/trailing whitespace

Remove all spaces and split

Regular‑expression matching

String splitting

Case conversion

String reversal

Substring presence checks

Suffix checks

Array Operations

Reverse an array

Remove duplicate elements

Randomly shuffle elements

Loop Constructs

Numeric loops

Variable‑based loops

Array‑based loops

File content iteration

Directory traversal

File Handling

Read file into a string

Read file line‑by‑line into an array

Read first n lines

Read last n lines

Create an empty file

Path Utilities

Extract directory name from a full path

Extract file name from a full path

Example: Trimming Whitespace

trim_string() {
    # Usage: trim_string "   example   string   "
    : "${1#${1%%[![:space:]]*}}"
    : "${_%${1%%[![:space:]]*}}"
    printf '%s
' "$_"
}

Calling the function:

trim_string "    Hello,  World    "
# Output: Hello,  World

Example: Looping Constructs

# Loop from 0 to 100 (no variable support)
for i in {0..100}; do
    printf '%s
' "$i"
done

# Loop with a variable limit
VAR=50
for ((i=0;i<=VAR;i++)); do
    printf '%s
' "$i"
done

# Loop over array elements
for element in "${arr[@]}"; do
    printf '%s
' "$element"
done

Conclusion

The Pure Bash Bible is a concise reference for many common shell tasks, providing dependency‑free solutions that can be looked up quickly. For the full list of commands and additional built‑ins, refer to the GitHub repository linked above.