Making scripts executable (chmod +x) in Bash Scripting - Mini Project: Build & Apply

Making a Bash Script Executable with chmod +x

📖 Scenario: You have written a simple bash script to greet users. Now, you want to run it directly from the terminal without typing bash before the script name.

🎯 Goal: Make your bash script executable using the chmod +x command and run it directly.

📋 What You'll Learn

Create a bash script file named greet.sh with a greeting message.

Add execute permission to the script using chmod +x greet.sh.

Run the script directly using ./greet.sh.

💡 Why This Matters

🌍 Real World

Making scripts executable is essential to run automation tasks, system maintenance scripts, or any custom commands quickly without typing the interpreter every time.

💼 Career

System administrators, DevOps engineers, and developers often write and run executable scripts to automate workflows and manage servers efficiently.

1

Create the bash script file

Create a file named greet.sh and write the following lines exactly:
#!/bin/bash
echo "Hello, welcome to the bash scripting world!"

Bash Scripting

# Create a file named greet.sh with the shebang and echo command
# Your code here

Hint

The first line #!/bin/bash tells the system this is a bash script.

2

Add execute permission to the script

Use the command chmod +x greet.sh to add execute permission to the greet.sh file.

Bash Scripting

#!/bin/bash
echo "Hello, welcome to the bash scripting world!"
# Add execute permission using chmod +x greet.sh
# Your code here

Hint

Use chmod +x followed by the script file name to make it executable.

3

Run the script directly

Run the script directly by typing ./greet.sh in the terminal.

Bash Scripting

#!/bin/bash
echo "Hello, welcome to the bash scripting world!"

chmod +x greet.sh

# Run the script directly
# Your code here

Hint

Use ./ before the script name to run it from the current directory.

4

See the output of the script

Write a command to display the output of running ./greet.sh. The output should be:
Hello, welcome to the bash scripting world!

Bash Scripting

#!/bin/bash
echo "Hello, welcome to the bash scripting world!"

chmod +x greet.sh

./greet.sh

# Print the output of the script
# Your code here

Hint

Running ./greet.sh will print the greeting message to the terminal.

Practice

1. What does the command chmod +x script.sh do in bash scripting?

easy

A. Makes the script script.sh executable so it can be run directly.

B. Deletes the script script.sh from the system.

C. Copies the script script.sh to another location.

D. Changes the owner of the script script.sh.

Solution

1. Step 1: Understand the chmod command

   The chmod command changes file permissions in Linux and Unix systems.

2. Step 2: Interpret the +x option

   The +x option adds execute permission, allowing the file to be run as a program.

3. Final Answer:

   Makes the script script.sh executable so it can be run directly. -> Option A

4. Quick Check:

   chmod +x means add execute permission [OK]

Hint: Remember +x means add execute permission [OK]

Common Mistakes:

• Confusing execute permission with deleting files
• Thinking chmod copies files
• Mixing up ownership change with permission change

2. Which of the following is the correct syntax to make a script named run.sh executable?

easy

A. chmod x run.sh

B. chmod x+ run.sh

C. chmod -x run.sh

D. chmod +x run.sh

Solution

1. Step 1: Recall the correct order of options in chmod

   The correct syntax to add execute permission is chmod +x filename.

2. Step 2: Check each option

   chmod +x run.sh matches the correct syntax exactly; others have incorrect order or missing symbols.

3. Final Answer:

   chmod +x run.sh -> Option D

4. Quick Check:

   Correct syntax is chmod +x filename [OK]

Hint: Use chmod +x filename to add execute permission [OK]

Common Mistakes:

• Placing + and x in wrong order
• Using -x which removes execute permission
• Omitting the + sign

3. Given a script hello.sh without execute permission, what will be the output of the command sequence below?

ls -l hello.sh
chmod +x hello.sh
ls -l hello.sh

medium

A. Both ls -l commands show execute permission.

B. The first ls -l shows no execute permission; the second shows execute permission added.

C. The first ls -l shows execute permission; the second removes it.

D. Both ls -l commands show no execute permission.

Solution

1. Step 1: Understand initial permissions

   Initially, hello.sh has no execute permission, so ls -l shows no 'x' in permissions.

2. Step 2: Apply chmod +x and check again

   After running chmod +x hello.sh, execute permission is added, so the second ls -l shows 'x' in permissions.

3. Final Answer:

   The first ls -l shows no execute permission; the second shows execute permission added. -> Option B

4. Quick Check:

   Adding +x updates permissions visible in ls -l [OK]

Hint: Check permissions before and after with ls -l [OK]

Common Mistakes:

• Assuming execute permission is present initially
• Thinking chmod +x removes execute permission
• Not noticing permission changes in ls -l

4. You try to run a script myscript.sh but get a "Permission denied" error. Which command fixes this issue?

medium

A. chmod -x myscript.sh

B. chmod +r myscript.sh

C. chmod +x myscript.sh

D. chmod 000 myscript.sh

Solution

1. Step 1: Identify cause of "Permission denied"

   The error usually means the script lacks execute permission.

2. Step 2: Add execute permission

   Using chmod +x myscript.sh adds execute rights, allowing the script to run.

3. Final Answer:

   chmod +x myscript.sh -> Option C

4. Quick Check:

   Add execute permission to fix "Permission denied" [OK]

Hint: Add execute permission with chmod +x [OK]

Common Mistakes:

• Using -x which removes execute permission
• Setting permissions to 000 which denies all access
• Adding only read permission (+r) which doesn't allow execution

5. You have a script deploy.sh that you want to run directly by typing ./deploy.sh. However, it still says "Permission denied" after chmod +x deploy.sh. What could be the reason?

hard

A. The script is on a mounted filesystem that does not support execute permissions.

B. You forgot to add read permission with chmod +r deploy.sh.

C. You need to rename the script to deploy.exe.

D. You must run the script with bash deploy.sh instead of ./deploy.sh.

Solution

1. Step 1: Confirm execute permission is set

   Since chmod +x deploy.sh was run, the script should have execute permission.

2. Step 2: Consider filesystem limitations

   Some mounted filesystems (like FAT32 or network shares) do not support Unix execute permissions, causing "Permission denied" despite chmod +x.

3. Step 3: Evaluate other options

   Adding read permission is usually default; renaming to .exe is irrelevant in Linux; running with bash works but does not explain the permission error when running ./deploy.sh.

4. Final Answer:

   The script is on a mounted filesystem that does not support execute permissions. -> Option A

5. Quick Check:

   Filesystem may block execute permission despite chmod [OK]

Hint: Check if filesystem supports execute permissions [OK]

Common Mistakes:

• Assuming chmod always works on all filesystems
• Thinking read permission alone allows execution
• Confusing script name extension with execution ability