???????shell
???????????????????????????????????kernel????????????????????????????????????????????????????????????shell??????ó????????????????????????????????????? shell??????????????????????????????????shell?????????????????????????????????
????????shell????????????н?????????????????????shell???????Linux????????????bash??
???????shell????????????????????????Щ???shell?????????????????????/etc/shells ?е?/sbin/nologin ??????????????Linux?????/etc/passwd????????????????shell??????????shell???????/sbin/nologin??????/bin/bash??????????????????
????????bash
????bash ???????
????1??history
??????????書??????????????й?????????????????????ε????????????д??~/.bash_history?У??′ε???????????ε?????????
????2??Tab????????????????
????3??alias
?????????????alias hsnn='ls -al' ???????hsnn ??????ls -al ????
????4??shell script
??????????????????????????
????5?????????????????????
????6????????Wildcard??
????*  _
????????bash??????????
????bash?????????????cd umask ???????type ????????????????????
????type -t  name
????file:??????
????alias:?????????????
????builtin:bash ????????
????type -p name  name?????????????????·??????which
????type -a name  ?г?PATH?????а???name??????????alias