nohup

Overview

The nohup command runs a command immune to hangups, with output to a non-tty. It allows processes to continue running after the terminal is closed or the user logs out.

Syntax

nohup command [arguments]

Common Options

Option Description
--help Show help
--version Show version
-p Print PID
-u Unbuffered output

Output Handling

File Description
nohup.out Default output
~/nohup.out Home directory
./nohup.out Current directory
/dev/null Discard output

Key Use Cases

  1. Background jobs
  2. Long-running tasks
  3. Remote execution
  4. Batch processing
  5. System maintenance

Examples with Explanations

Example 1: Basic Usage

nohup command &

Run in background

Example 2: Custom Output

nohup command > output.log 2>&1 &

Redirect output

Example 3: Discard Output

nohup command >/dev/null 2>&1 &

No output file

Common Usage Patterns

  1. Long process:

    nohup ./script.sh &

  2. With logging:

    nohup command > log.txt &

  3. Background job:

    nohup command & echo $!

Process Management

  1. Background running
  2. Signal handling
  3. Output redirection
  4. Process isolation
  5. Job control

Additional Resources

Best Practices

  1. Redirect output
  2. Check process
  3. Use job control
  4. Monitor resources
  5. Clean up files

Security Considerations

  1. Process ownership
  2. File permissions
  3. Output handling
  4. Resource limits
  5. System access

Troubleshooting

  1. Process status
  2. Output files
  3. Permission issues
  4. Signal handling
  5. Resource usage

Common Issues

  1. Output location
  2. Process termination
  3. Signal handling
  4. File permissions
  5. Resource limits