From man bash:

       -n string
              True if the length of string is non‐zero.

Examples:

# expected
$ var=""; [ -n "$var" ]; echo $?
1

# unexpected?
$ var=""; [ -n $var ]; echo $?
0

Here we see that -n with unquoted variable containing empty string returns true. Why?

Why $var is required to be quoted here?

From man bash:

-n string
    True if the length of string is non‐zero.

Examples:

# expected
$ var=""; [ -n "$var" ]; echo $?
1

# unexpected?
$ var=""; [ -n $var ]; echo $?
0

Here we see that -n with unquoted variable containing empty string returns true. Why?

Why is $var required to be quoted here?

From man bash:

       -n string
              True if the length of string is non‐zero.

Examples:

# expected
$ var=""; [ -n "$var" ]; echo $?
1

# unexpected?
$ var=""; [ -n $var ]; echo $?
0

Here we see that -n with unquoted variable returns true. Why?

Why $var is required to be quoted here?

From man bash:

       -n string
              True if the length of string is non‐zero.

Examples:

# expected
$ var=""; [ -n "$var" ]; echo $?
1

# unexpected?
$ var=""; [ -n $var ]; echo $?
0

Here we see that -n with unquoted variable containing empty string returns true. Why?

Why $var is required to be quoted here?