Linux Command 6

text

　　$echo string display string

　　$echo string | cut -c5-7 Cut out the 5th to 7th columns of the text

　　$echo string | grep regex displays lines containing regular expression regex

　　$echo string | grep -o regex displays substrings matching regular regex

time and date

　　$date current date and time   

　　$date +"%Y-%m-%d_%T" displays the date and time in the format of YYYY-MM-DD_HH:MM:SS (for the format, please refer to $man date)   

　　$date --date="1999-01-03 05:30:00" 100 days Displays the date and time 100 days backward from 1900-01-03 05:30:00

　　$sleep 300 sleep for 300 seconds