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Janak Shrestha
Janak Shrestha

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Script Execution Permissions

#linux

In a bid to automate backup processes, the xFusionCorp Industries sysadmin team has developed a new bash script named xfusioncorp.sh. While the script has been distributed to all necessary servers, it lacks executable permissions on App Server 2 within the Stratos Datacenter.

Your task is to grant executable permissions to the /tmp/xfusioncorp.sh script on App Server 2. Additionally, ensure that all users have the capability to execute it.

Solution

Step 1: Connect to App Server 2 (stapp02) 

ssh steve@stapp02
# Password: Am3ric@
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Step 2: Switch to root or use sudo 

sudo su -
# Password: Am3ric@
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Step 3: Check current permissions 

ls -la /tmp/xfusioncorp.sh
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Step 4: Grant executable permissions to all users 

chmod a+x /tmp/xfusioncorp.sh
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Command breakdown:

  • chmod: Change file permissions
  • a+x: Add execute permission for all users (owner, group, others)
    • a = all users
    • + = add permission
    • x = execute permission

Alternative approaches:

# Using numeric mode (755 gives rwxr-xr-x)
chmod 755 /tmp/xfusioncorp.sh

# Using symbolic mode (same as a+x)
chmod +x /tmp/xfusioncorp.sh

# Explicitly for all users
chmod u+x,g+x,o+x /tmp/xfusioncorp.sh
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Step 5: Verify the permissions 

ls -la /tmp/xfusioncorp.sh
# Should show: -rwxr-xr-x or -rwxr-xr-x

# Verify all users can execute
# As root, test execution
/tmp/xfusioncorp.sh

# As another user (if exists)
su - steve -c "/tmp/xfusioncorp.sh"
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Complete One-Line Commands

From jump host with password: 

echo 'Am3ric@' | ssh steve@stapp02 "sudo -S chmod a+x /tmp/xfusioncorp.sh && sudo -S ls -la /tmp/xfusioncorp.sh"
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From jump host using heredoc: 

ssh steve@stapp02 << 'EOF'
echo 'Am3ric@' | sudo -S bash -c '
echo "Current permissions:"
ls -la /tmp/xfusioncorp.sh
echo ""
echo "Adding execute permissions for all users..."
chmod a+x /tmp/xfusioncorp.sh
echo ""
echo "Updated permissions:"
ls -la /tmp/xfusioncorp.sh
echo ""
echo "✓ Execute permission granted successfully"
'
EOF
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Step-by-Step Interactive Commands 

# Connect to stapp02
ssh steve@stapp02
# Enter password: Am3ric@

# Become root
sudo su -
# Enter password: Am3ric@

# Check current permissions
ls -la /tmp/xfusioncorp.sh

# Example output before:
# -rw-r--r-- 1 root root 1024 Jul 03 10:00 /tmp/xfusioncorp.sh
# (No execute permissions)

# Add execute permissions for all users
chmod a+x /tmp/xfusioncorp.sh

# Verify permissions
ls -la /tmp/xfusioncorp.sh

# Expected output after:
# -rwxr-xr-x 1 root root 1024 Jul 03 10:00 /tmp/xfusioncorp.sh
# (Execute permissions for all)

# Test execution
/tmp/xfusioncorp.sh

# Exit back
exit
exit
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Permission Breakdown

Understanding the permissions:

Mode Owner Group Others Description
Before: -rw-r--r-- Read/Write Read Read No execute permission
After: -rwxr-xr-x Read/Write/Execute Read/Execute Read/Execute Execute permission for all

Various chmod options: 

# Add execute for all (same as a+x)
chmod +x /tmp/xfusioncorp.sh

# Add execute for owner only
chmod u+x /tmp/xfusioncorp.sh

# Add execute for group only
chmod g+x /tmp/xfusioncorp.sh

# Add execute for others only
chmod o+x /tmp/xfusioncorp.sh

# Remove execute for all
chmod a-x /tmp/xfusioncorp.sh

# Set exact permissions (755 = rwxr-xr-x)
chmod 755 /tmp/xfusioncorp.sh

# Set exact permissions (777 = rwxrwxrwx)
chmod 777 /tmp/xfusioncorp.sh
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Verification Commands

Run these to verify everything is correct:

# 1. Check permissions
ls -la /tmp/xfusioncorp.sh

# 2. Check file type and permissions in detail
stat /tmp/xfusioncorp.sh

# 3. Verify it's executable by owner
test -x /tmp/xfusioncorp.sh && echo "✓ Executable by owner" || echo "✗ Not executable by owner"

# 4. Check if executable by all users
# As current user
/tmp/xfusioncorp.sh

# Check if others can execute (if another user exists)
sudo -u steve /tmp/xfusioncorp.sh

# 5. Get octal permissions
stat -c "%a %n" /tmp/xfusioncorp.sh
# Should output: 755 /tmp/xfusioncorp.sh or 755

# 6. Check script content
cat /tmp/xfusioncorp.sh

# 7. Verify script syntax
bash -n /tmp/xfusioncorp.sh
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Expected Output 

[root@stapp02 ~]# ls -la /tmp/xfusioncorp.sh
-rw-r--r-- 1 root root 1024 Jul 03 10:00 /tmp/xfusioncorp.sh

[root@stapp02 ~]# chmod a+x /tmp/xfusioncorp.sh

[root@stapp02 ~]# ls -la /tmp/xfusioncorp.sh
-rwxr-xr-x 1 root root 1024 Jul 03 10:00 /tmp/xfusioncorp.sh

[root@stapp02 ~]# /tmp/xfusioncorp.sh
[Script output...]

[root@stapp02 ~]# stat -c "%a %n" /tmp/xfusioncorp.sh
755 /tmp/xfusioncorp.sh
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Troubleshooting

  1. "No such file or directory": 
   # Check if script exists
   ls -la /tmp/xfusioncorp.sh
   # If not, check alternative locations
   find /tmp -name "xfusioncorp.sh" 2>/dev/null
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  1. "Permission denied" when changing permissions: 
   # Use sudo to gain required permissions
   sudo chmod a+x /tmp/xfusioncorp.sh
   # Or become root
   sudo su -
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  1. Script doesn't execute even with permissions: 
   # Check if script has correct shebang
   head -1 /tmp/xfusioncorp.sh
   # Should be: #!/bin/bash or similar

   # Run with bash explicitly
   bash /tmp/xfusioncorp.sh
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  1. Need to preserve other permissions: 
   # Only add execute, don't change read/write
   chmod a+x /tmp/xfusioncorp.sh
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Additional Security Considerations

Less permissive approaches (if required): 

# Owner can execute only
chmod u+x /tmp/xfusioncorp.sh
chmod go-x /tmp/xfusioncorp.sh
# Result: -rwxr--r--

# Owner and group can execute
chmod u+x,g+x /tmp/xfusioncorp.sh
chmod o-x /tmp/xfusioncorp.sh
# Result: -rwxr-xr--
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Verify script safety: 

# Check script content
cat /tmp/xfusioncorp.sh

# Check for suspicious commands
grep -E "(rm -rf|dd|mkfs|>/dev)" /tmp/xfusioncorp.sh

# Test script in safe mode
bash -n /tmp/xfusioncorp.sh  # Syntax check
bash -x /tmp/xfusioncorp.sh  # Debug mode
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Complete Solution Summary

The task has been completed on App Server 2 (stapp02):

  • ✅ Script located at /tmp/xfusioncorp.sh
  • ✅ Execute permissions added for all users (chmod a+x)
  • ✅ Permissions changed from -rw-r--r-- to -rwxr-xr-x
  • ✅ Verified script is executable by all users
  • ✅ Script can now be executed by any user on the system

The bash script xfusioncorp.sh is now ready for use in the automated backup processes as required by the xFusionCorp Industries sysadmin team.

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