Chap 9. A Programmable Shell

Chap 9. A Programmable Shell

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* Shell -> run as interpreter (an essential part of UNIX)

* Shell run as two way ( sh ~~ / chmod +x )

* smsh(fork - wait - execlp)

* smsh2 - if~then~else~fi (controlCheck - smsh1)

* smsh3 - variable(set- VLlist, = - VLstore, export)

* smsh4 - envVar

* smsh.ver1

* Shell control ( if ~ then ~ else ~ fi)

* smsh.ver2

* variable ( local / env ) - set, assign, export, unset

* VLlist, VLStore(var, val), VLexport(var)

* smsh.ver3

* environ (char**) 

* smsh.ver4