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/* A Simple Shell |
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* |
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* Douglas Thrift |
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*/ |
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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 <sys/types.h> |
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#include <unistd.h> |
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int main(argc, argv, envp) |
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int argc; |
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char **argv, envp; |
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{ |
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char command[BUFSIZ] = ""; |
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do |
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{ |
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/* strtok(3) */ |
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char *file = strtok(command, " "); |
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if (file) |
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/* strcmp(3) */ |
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if (strcmp(file, "cd") == 0) |
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{ |
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/* strtok */ |
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char *directory = strtok(NULL, " "); |
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if (!directory) |
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/* getenv(3) */ |
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directory = getenv("HOME"); |
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/* chdir(2) */ |
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if (chdir(directory) == -1) |
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/* perror(3) */ |
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perror(argv[0]); |
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} |
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else |
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{ |
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unsigned count = 1; |
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/* malloc(3) */ |
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char **args = malloc(sizeof (char *) * 2); |
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pid_t command, value; |
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args[0] = file; |
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/* strtok(3) */ |
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while (args[count++] = strtok(NULL, " ")) |
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/* realloc(3) */ |
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douglas |
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args = realloc(args, sizeof (char *) * (count + 1)); |
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douglas |
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/* fork(2) */ |
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switch (command = fork()) |
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{ |
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case -1: |
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/* perror(3) */ |
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perror(argv[0]); |
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return 1; |
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case 0: |
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/* execvp(3) */ |
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execvp(file, args); |
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/* perror(3) */ |
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perror(argv[0]); |
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return 1; |
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} |
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/* wait(2) */ |
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while ((value = wait(NULL)) != command) |
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if (value == -1) |
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{ |
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/* perror(3) */ |
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perror(argv[0]); |
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return 1; |
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} |
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/* free(3) */ |
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free(args); |
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} |
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/* printf(3) */ |
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printf("$ "); |
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/* fflush(3) */ |
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fflush(stdout); |
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} |
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/* gets(3) */ |
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while (gets(command)); |
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return 0; |
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} |
