How to use the command 'nproc' (with examples)

The nproc command prints the number of processing units available, typically referring to CPUs. It is a useful command in various scenarios, such as determining the number of processing units for resource allocation or monitoring system performance. This article provides examples illustrating the different use cases of the nproc command.

Use case 1: Display the number of available processing units

Code:

nproc

Motivation: This use case is helpful when you need to know the number of processing units available on the system. It can be useful in resource allocation scenarios, such as deciding how many parallel tasks can be executed simultaneously.

Explanation: In this use case, the nproc command is used without any arguments. It directly queries and prints the number of processing units available on the system, typically the number of CPUs.

Example output:

4

The output indicates that there are 4 processing units (CPUs) available on the system.

Use case 2: Display the number of installed processing units, including any inactive ones

Code:

nproc --all

Motivation: This use case helps to determine the total count of installed processing units, including any inactive or disabled ones. It may be useful in troubleshooting scenarios or when detailed information about the system’s hardware configuration is required.

Explanation: The --all option is used with the nproc command to display the count of all installed processing units, regardless of their active status. It provides a full overview of the available hardware resources.

Example output:

8

The output shows that there are 8 installed processing units (CPUs), including both active and inactive ones.

Use case 3: Subtract a given number of units from the returned value

Code:

nproc --ignore count

Motivation: This use case allows you to dynamically adjust the reported number of processing units by subtracting a specified count. It can be helpful when you need to allocate a specific number of processing units for a task and want to exclude a certain number of units from the calculation.

Explanation: The --ignore option followed by a numeric value, count, is used with the nproc command to subtract a given number of units from the returned value. The output will be decreased by the specified count.

Example output: Suppose the original output of nproc is 8, and we want to subtract 2 units:

6

The output shows that after subtracting 2 units, the adjusted count is 6 processing units (CPUs).

Conclusion:

The nproc command is a handy tool for obtaining information about the number of processing units available on a system. It can assist in tasks such as resource allocation, system monitoring, and troubleshooting. By understanding the different use cases illustrated in this article, you can make effective use of the nproc command in various scenarios.