myshell specification

• unix shell command를 실행하는 myshell 구현

1. cd 구현
2. exit 구현
3. 백그라운드 실행 구현
4. SIGCHLD로 자식 프로세스 wait() 시 프로세스가 온전하게 수행되도록 구현
5. ^C, ^＼사용시쉘이종료되지않도록구현
6. redirection 구현
7. pipe 구현 (파이프는 하나만 동작하도록 구현)

• pseudocode variable where Ignore SIGCHLD Define sigaction act1 ignoring SIGQUIT Define sigaction act2 ignoring SIGINT LOOP forever Print(“prompt> “) Get commandline Parse commandline in order to know if < or > is included or not: redirection parsing IF ‘&’ is included in commandline THEN where <-background Make command vector IF command is ‘exit’ THEN terminate myshell Make child process SWITCH case child proc : IF ‘<’ is included in command THEN duplicate fd of RDONLY opened file to STDIN IF ‘>’ is included in command THEN duplicate fd of WRONLY opened file to STDOUT Set act1.sa_handler to SIG_DFL Set act2.sa_handler to SIG_DFL IF command is not ‘cd’ THEN execute commandline exit case parent proc : IF command is ‘cd’ THEN execute commandline IF where is background THEN restart LOOPwait child proc