> ## Documentation Index
> Fetch the complete documentation index at: https://docs.syntblaze.com/llms.txt
> Use this file to discover all available pages before exploring further.
# Bash Comment
A Bash comment is a lexical construct that instructs the shell interpreter to ignore specific text during the parsing and execution phases. A comment is initiated by an unquoted hash character (`#`) appearing at the beginning of a word, and it terminates unconditionally at the next newline character (`\n`). Backslashes inside a comment do not escape the newline; they are treated as literal characters.
When the Bash parser encounters a `#` at the start of a line or preceded by unquoted whitespace or metacharacters, it treats that character and all subsequent characters on the same physical line as a single token to be discarded before command execution.
## Syntax and Scope
Comments can be placed at the beginning of a line or inline following a command.
```bash theme={"dark"}
# This is a full-line comment. The parser ignores this entire line.
command_name --flag # This is an inline comment. The parser ignores text after the hash.
```
## Lexical Exceptions
The `#` symbol loses its comment-initiating property and is treated as a literal character if it is enclosed in single quotes (`'`), double quotes (`"`), escaped with a backslash (`\`), or if it appears anywhere other than the beginning of a word.
```bash theme={"dark"}
echo "The # symbol here is parsed as part of the string literal."
echo 'Another literal # character.'
echo file#name.txt # The first # is literal because it is not at the beginning of a word.
echo \# # The first # is escaped and literal. The second # starts the comment.
```
## Multi-line Comments
Bash does not possess a native block-comment operator (such as `/* ... */` found in C-family languages). To span comments across multiple lines, the standard approach is to prefix every line with the `#` character.
```bash theme={"dark"}
# Line one of the comment block
# Line two of the comment block
# Line three of the comment block
```
To bypass prefixing every line, developers often simulate block comments by combining the null utility (`:`), which does nothing and returns a `0` exit status, with a Here Document (`<<`).
```bash theme={"dark"}
: <<'EOF'
The shell parses this block as a string literal passed to the null command.
Because the null command ignores its standard input, this text is effectively
treated as a multi-line comment. Quoting the 'EOF' delimiter prevents parameter
expansion within the block.
EOF
```
## The Shebang (`#!`) Directive
If the `#` character is immediately followed by an exclamation mark (`!`) at byte zero (the absolute beginning) of a script file, it forms a magic number (`0x23 0x21`) known as a shebang. While syntactically resembling a comment to the Bash interpreter, the shebang is a directive read by the operating system's program loader to determine which interpreter to use for executing the file.
```bash theme={"dark"}
#!/usr/bin/env bash
# The line above is a shebang directive, not a standard comment.
```
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