[[ ]]

Use

[[ -e "$path" ]]

What It Does

[[ ]] is Bash’s conditional expression syntax. It tests strings, files, numbers, and patterns, then returns success or failure.

File Tests

[[ -e "$path" ]]
[[ -f "$path" ]]
[[ -d "$path" ]]
[[ -x "$path" ]]

• -e: path exists.
• -f: regular file.
• -d: directory.
• -x: executable or searchable.

String Tests

[[ -z "$name" ]]
[[ -n "$name" ]]
[[ "$name" == "Ada" ]]
[[ "$name" == A* ]]

• -z: empty string.
• -n: non-empty string.
• ==: string match.
• Right side patterns such as A* are Bash patterns when unquoted.

Numeric Tests

[[ "$count" -gt 0 ]]
[[ "$count" -eq 10 ]]

Use -gt, -lt, -eq, -ne, -ge, and -le for integer comparisons.

Watch Out

• Keep spaces after [[ and before ]].
• Quote variables unless you intentionally want pattern matching.
• [[ ]] is Bash syntax, not portable /bin/sh syntax.

Docs Pointers

• Run help [[.
• Read conditionals, quoting, and if.