Linux Shell Scripting 3

Question 1

In bash, which operator tests whether a string is non-empty?

Accepted Answer

[ -n "$var" ]

Answer

`-n` returns true if the string length is nonzero; `-z` tests for empty string.

Question 2

What will `echo ${#myvar}` print if `myvar="hello"`?

Accepted Answer

5

Answer

`${#varname}` expands to the length (number of characters) of the variable's value.

Question 3

Which line should appear at the very top of a bash script to specify the interpreter?

Accepted Answer

#!/bin/bash

Answer

The shebang `#!/bin/bash` tells the kernel which interpreter to use when the script is executed directly.

Question 4

How do you pass the value of variable `name` to a script as its first argument and access it inside?

Accepted Answer

./script.sh "$name"; access as $1

Answer

Arguments are passed on the command line and accessed inside the script as positional parameters `$1`, `$2`, etc.

Question 5

What is the effect of `trap 'rm -f /tmp/tmpfile' EXIT` in a script?

Accepted Answer

Runs the cleanup command whenever the script exits for any reason

Answer

`trap CMD EXIT` registers a command to run automatically whenever the script exits, enabling reliable cleanup.

Linux Practice Test