"tput: No value for $TERM and no -T specified " error logged by CRON process

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07-10-2024

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Decoding the "tput: No value for $TERM and no -T specified" Error in CRON Jobs

Have you ever encountered the cryptic error "tput: No value for $TERM and no -T specified" while running a cron job? This error often appears in scripts that use tput commands, which are responsible for manipulating terminal settings and controlling display properties.

Understanding the Error

The tput command relies on the environment variable $TERM to determine the type of terminal being used. When a cron job is executed, the default environment is often minimal, and the $TERM variable is usually not set. This leads to the error because tput cannot find the necessary information to perform its operations.

Scenario and Code Example

Let's consider a simple cron job that uses tput to clear the screen:

# crontab entry
*/5 * * * * /path/to/your/script.sh

# script.sh
#!/bin/bash

tput clear
echo "Hello, world!"

This script aims to run every 5 minutes and clear the terminal before displaying a message. However, when this job is executed, it will likely throw the "tput: No value for $TERM and no -T specified" error.

Solutions and Insights

There are several ways to fix this error:

• Specify the terminal type: Use the -T flag with tput to explicitly set the terminal type. For example:

  tput -T xterm clear
  

  This tells tput to treat the terminal as an xterm, a common terminal emulator.

• Set the $TERM environment variable: You can set the $TERM variable in your cron job before executing the script:

  # crontab entry
  */5 * * * * TERM=xterm /path/to/your/script.sh
  

  This approach explicitly defines the terminal type in the cron job environment.

• Use alternative methods: If your script only uses tput for basic operations like clearing the screen, you can consider using alternative methods like echo or printf. For example:

  # script.sh
  #!/bin/bash
  
  echo -e "\033c"  # Clear the screen
  echo "Hello, world!"
  

  This approach avoids the tput dependency completely.

Additional Notes

• It's crucial to choose the correct terminal type for your environment. If you're unsure, consult the documentation of your specific terminal emulator.
• While the solutions above address the error, consider using a more robust approach to handle terminal interactions in your cron jobs. This may involve checking for the existence of the $TERM variable and providing a default value if needed.

Conclusion

The "tput: No value for $TERM and no -T specified" error can be easily resolved by understanding the underlying problem and utilizing appropriate solutions. By setting the terminal type explicitly, using alternative methods, or handling the environment correctly, you can ensure your cron jobs execute smoothly and achieve the desired output.