77 lines
1.6 KiB
C
77 lines
1.6 KiB
C
/* This file is part of the sample code and exercises
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* used by the class "Advanced Programming in the UNIX
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* Environment" taught by Jan Schaumann
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* <jschauma@netmeister.org> at Stevens Institute of
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* Technology.
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*
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* This file is in the public domain.
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*
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* You don't have to, but if you feel like
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* acknowledging where you got this code, you may
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* reference me by name, email address, or point
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* people to the course website:
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* https://stevens.netmeister.org/631/
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*/
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/*
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* World's simplest shell.
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* Loops, reads input and tries to execute it.
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* Note: no tokenization, can be ^C'd, but does look at PATH
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*
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* ./simple-shell
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* $$ ls
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* $$ ls -l # error
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* $$ ^C
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*
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*/
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sysexits.h>
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#include <unistd.h>
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char *
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getinput(char *buffer, size_t buflen) {
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printf("$$ ");
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return fgets(buffer, buflen, stdin);
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}
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int
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main(int argc, char **argv) {
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char buf[BUFSIZ];
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pid_t pid;
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int status;
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/* cast to void to silence compiler warnings */
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(void)argc;
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(void)argv;
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while (getinput(buf, sizeof(buf))) {
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buf[strlen(buf) - 1] = '\0';
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if((pid=fork()) == -1) {
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fprintf(stderr, "shell: can't fork: %s\n",
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strerror(errno));
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continue;
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} else if (pid == 0) { /* child */
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execlp(buf, buf, (char *)0);
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fprintf(stderr, "shell: couldn't exec %s: %s\n", buf,
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strerror(errno));
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exit(EX_UNAVAILABLE);
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}
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/* parent waits */
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if ((pid=waitpid(pid, &status, 0)) < 0) {
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fprintf(stderr, "shell: waitpid error: %s\n",
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strerror(errno));
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}
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}
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exit(EX_OK);
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}
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