time

The "time" command line tool is used to determine the execution time of a given command or program. It measures the elapsed real time, user CPU time, and system CPU time of the specified command. By default, it prints the time statistics to the standard error stream after the command finishes executing. It is particularly useful for identifying the performance of a program or script. The real time represents the actual wall-clock time taken by the command to run. The user CPU time measures the amount of CPU time spent in user-mode code within the command. The system CPU time represents the amount of CPU time spent in system-mode code by the command. The "time" command can be used to compare the performance of different commands or versions of the same command. It also allows for more advanced functionality, such as formatting the output or specifying the maximum amount of CPU time allowed for the command to run. Overall, "time" is a versatile command line tool for analyzing the execution time of programs and optimizing their performance.