View the number of threads of a process in CentOS

Sometimes it is necessary to determine the number of threads currently running in the process, so the following methods are worth using.

1. query by process Number:

# Pstree-p process number

# Top-Hp Process number

2. query by process name:

# Pstree-p 'ps-e | grep server | awk '{print $1 }''

# Pstree-p 'ps-e | grep server | awk '{print $1} ''| wc-l

Pipeline and command replacement are used here,

I only learned about command replacement today. That is to say, commands enclosed by ''are executed first, and their output is used as parameters of other commands,

The output (process number) of ps-e | grep server | awk '{print $1}' is used as the pstree-p parameter.

Pipeline and command replacement are different:

Pipeline: Pipeline symbol "|" the output of the left command serves as the input of the right command

Command replacement: Use the command output in the Command replacement character "'' "as a parameter for the corresponding positions of other commands.