variable

    1. # work
    2. foo=bar
    3. echo $foo
    4. > bar
    7. # not work
    8. foo = bar
    9. > command not found: foo
    11. echo "value is $foo"
    12. > value is bar

    reserved command

    1. # the name of the script
    2. $0
    4. # the first-ninth argument that scirpt takes
    5. $1-9
    7. # the last argument of the previous command
    8. $_
    10. mkdir test
    11. cd $_
    13. # get the error code from the previous command
    14. $?
    16. # get the previous command
    17. !!

    functions

    1. # mcd.sh
    2. mcd () {
    3.     # $1 means the first argument of input
    4.     mkdir -p "$1"
    5.   cd "$1"
    6. }
    8. # execute this script in our shell and load it
    9. source msc.sh
    11. # now you can use the function in msc.sh defined
    12. mcd test