echo
Function: display a line of text (display a line of text)
Example:
echo view help
Example:
grep
The Linux grep (global regular expression) command is used to find qualified strings or regular expressions in files. If no file name is specified, or if the file name - is given, the grep command reads data from the standard input device.
More explanations and examples
grammar
grep [options] pattern [files]- pattern - Indicates the string or regular expression to look for.
- files - Indicates the name of the file to be searched. Multiple files can be searched at the same time. If the files parameter is omitted, the data will be read from the standard input by default.
Example 1:
Explanation: Find the string named twinkle in greped.txt
Example 2:
Explanation: The anonymous pipeline | uses the output of the echo the world is nice command as the input data of the grep "the world" command.
ps
The Linux ps (full spelling in English: process status) command is used to display the status of the current process, similar to the task manager of windows.
More explanations and examples
grammar
ps [options] [--help]Example: Find the specified process format
ps -ef | grep 进程关键字Explanation: Display the process of php
