Linux shell ----- 1 variable $ #, $ @, $0, $1, $2

Linux shell ----- 1 variable $ #, $ @, $0, $1, $2 Description of the variable Description: $ Shell's PID (ProcessID) $! PID of the background Process last run by Shell $? End code of the last command (Return Value) $-Flag list Set using the Set command $ * List of all parameters. For example, when "$ *" is included in... $ N "to output all parameters. $ @ List of all parameters. For example, when "$ @" is included in "... All parameters are output in the form of "$ n. $ # Number of parameters added to Shell $ File Name of 0Shell itself $1 ~ $ N parameter values added to Shell. $1 is the 1st parameter, and $2 is the 2nd parameter .... Let's first write a simple script and then explain the meaning of each variable after execution # touch variable # vi variable script content is as follows :#! /Bin/shecho "number: $ #" echo "scname: $0" echo "first: $1" echo "second: $2" echo "argume: $ @ "Save and exit. Grant the script execution permission # chmod + x variable to execute the script #. /variable aa bbnumber: 2 scname :. /variablefirst: aasecond: bbargume: aa bb can be seen through the display results: $ # number of parameters passed to the script $0 is the name of the script itself $1 is the first parameter passed to the shell script $2 is the second parameter passed to the shell script $ @ is a list of all parameters passed to the script