RE: nice: cannot set niceness: Permission denied

nice: cannot set niceness: Permission denied
ionice: ioprio_set failed: Operation not permitted

Bobbel Asked on November 24, 2023 in uncategorized.
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1 Answers
The error messages you're encountering suggest that you're trying to change the priority of a process (nice value) or the I/O priority (ionice) without having the sufficient permissions to do so. Here is a detailed breakdown of what's happening and how to address it: 1. **`nice: cannot set niceness: Permission denied`**: - The `nice` command in UNIX-like systems is used to invoke a utility at a particular priority. The "niceness" levels range from -20 (most favorable scheduling) to 19 (least favorable). By default, regular users can only increase the "niceness" (make processes less favorable), but cannot decrease it (make processes more favorable). - If you're receiving this error as a regular user, it likely means you are trying to set a niceness level that is more favorable than the process's current level. - To solve this, you can either invoke the command with just `nice` without specifying a niceness value (which will increase the niceness by 10), or you can use `sudo` to run the command with superuser privileges (if you have access). For example: - Increase niceness (decrease priority) without specifying the value: ```bash nice command_to_run ``` - Specify the niceness value with superuser privileges: ```bash sudo nice -n -10 command_to_run ``` 2. **`ionice: ioprio_set failed: Operation not permitted`**: - The `ionice` command is used to set or get the I/O scheduling class and priority for a program. Similar to `nice`, but for I/O operations, allowing you to specify how much I/O bandwidth a process can consume. - If you're not the owner of the process or if you're not the superuser, you cannot change the I/O priority. - To address this, you would typically run the command as the root user or with `sudo`, for example: ```bash sudo ionice -c 2 -n 7 command_to_run ``` This sets the command `command_to_run` to use the "best-effort" scheduling class (`-c 2`) with a low priority (`-n 7`). Remember that modifying process priorities with `nice` and `ionice` should be done with caution, as setting the wrong priorities can lead to system performance degradation. These tools are often used when you have a good understanding of your system's load and you need to prioritize certain processes over others. For someone encountering this issue in the future who is looking to solve the `Permission denied` error for `nice` and `ionice`, make sure you understand your system's permission model and use `sudo` if you have the necessary rights and understand the implications of changing process priorities.
Answered on November 24, 2023.
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