What is the meaning of variable #,#,@,0,0,1,2,2,*,$$,$ in Linux?

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$# is the number of arguments passed to the script $ 0   is the name of the script itself $ 1   $ 2   [email protected] is a list of all parameters passed to the script $* is to display all parameters passed to the script in a single string, unlike positional variables, which can exceed 9 $$ is the current process ID number for the script to run $? is the exit state that displays the last command, 0

Difference:@@*

• Same point: All parameters are referenced
• Different points: only in double quotes. Suppose that three parameters were written when the script was run (stored in1123) then " 3) "*" is equivalent to "1123"（Mass transferHandedThe one Ginseng number ) ;" 3 "(pass a parameter), and" @ "is equivalent to"1""1 "" 2 "" $ $ "(three parameters passed)

Example One

# #dels. Sh
echo "number:$#" echo "Scname:$0" echo "First:" echo "Second:$2" echo "Argume:[email protected]" echo "Show Parm list:$*" echo "Show process id:$$" echo "Show Precomm stat: $?"

Execution results

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[@jihite]$ sh del.sh 123number:3scname:del.shfirst: 1second:2argume:123showparm list:1 23showprocess id:21057showprecomm stat: 0

Example Two

#!/bin/shnum=$ #name =$0echo "number: $num" echo "Scname: $name" echo $0echo $1echo $2for ((i=0; i< $num; i++)) do    Echo "$i" Doneecho "Argume:[email protected" "for key in [email Protected]do    echo $keydoneecho"-----------------"for key In "[email protected]" does    echo $keydoneecho "-----------------------------" for Key2 in $*do     echo $key 2doneecho " -----------------"for Key2 in" $* "Do     echo $key 2doneecho" show process id:$$ "Choecho" show Precomm stat: $? "

Execution results

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[@jihite]$ sh del.sh a b                                                      number:2scname:del.shdel.shab01argume:a bab-----------------ab-----------------------------ab-----------------a bshowprocess id:23582del.sh: line 37:cho: command not foundshowprecomm stat: 127

Problem:

echo #0 #1 can you use $i to express it?

Meaning of variable #,#,@,0,0,1,2,2,*,$$,$ in Linux