Initial commit

README.org

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+#+TITLE: GRU orsh - simple shell on C
+
+** Features:
+  - echo and pwd builtin
+  - working environment variables
+
+** How to build:
+  - cd src
+  - make
+  - orsh is executable of shell
+
+

src/Makefile

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+CC = gcc
+CFLAGS= -O2 -Wall -Wextra
+LFLAGS=
+
+SRCFILES= main.c
+OBJFILES= orsh
+
+.PHONY: all clean 
+
+all: main
+
+main: 
+	$(CC) $(CFLAGS) $(SRCFILES) -o $(OBJFILES) 
+

src/main.c

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+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/wait.h>
+
+int position = 0;
+char pwd[128]; // FIXME: change to PATH_MAX
+
+char **split_line(char *line) { 
+	int bufsize = 64;
+	position = 0;
+	char **tokens = malloc(bufsize * sizeof(char*));
+	char *token;
+
+	if (!tokens) {
+		fprintf(stderr, "orsh: allocation error\n");
+		exit(EXIT_FAILURE);
+	}
+
+	token = strtok(line, " ");
+	while (token != NULL) {
+		tokens[position] = token;
+		position++;
+		token = strtok(NULL, " ");
+	}
+	tokens[position] = NULL;
+	return tokens;
+}
+
+int execute(char **command, int status) {
+	status = 0;
+	pid_t pid, wpid;
+
+	pid = fork();
+	if (pid == 0) {
+		// Child process
+		if (execvp(command[0], command) == -1) {
+			perror("orsh");
+		}
+		status = 1; // FIXME: add error status
+		exit(EXIT_FAILURE);
+	} else if (pid < 0) {
+		// Error forking
+		perror("orsh");
+		status = 1; // FIXME: add error status
+	} else {
+		// Parent process
+		do {
+			wpid = waitpid(pid, &status, WUNTRACED); // FIXME: warning unused variable
+		} while (!WIFEXITED(status) && !WIFSIGNALED(status));
+	}
+	
+
+	return status;
+}
+
+int parse_command(char **command) { 	
+	int variable = 0;
+	int where_var[position - 1];
+	for (int i = 0; i <= position - 1; i++) { // Loop for checking if line has variable
+		if (command[i][0] == '$') {
+			where_var[i] = 1;
+			variable++;
+		}
+	}
+	if (variable >= 1) {
+		for (int i = 0; i <= position - 1; i++) {
+			if(where_var[i] == 1) {
+				command[i]++; // Deleting '$' char
+				command[i] = getenv(command[i]);
+			}
+		}
+	}
+
+	int status = 0; // FIXME: add status as argument (to know status of last command)
+
+	if (command[0][strlen(command[0]) - 1] == ';'){ // FIXME: parse all word not only first
+		command[0][strlen(command[0])-1] = '\0';
+	} else if (command[0][0] == ';'){ // Check if command is ; or first char of command is ;
+		command[0][0] = '\0'; 
+	}
+	
+	if (!strcmp(command[0], "exit")) { // FIXME: add switch statement (if possible)
+		printf("exit\n");
+		exit(0);
+	} else if (!strcmp(command[0], "echo")) {
+		for (int i = 1; i <= position - 1; i++) 
+			printf("%s ", command[i]);
+		printf("\n");
+		return 0;
+	} else if (!strcmp(command[0], "cd")) {
+		if (position == 1) {
+			printf("HOME todo\n");
+		} else if (position >= 3) {
+			printf("orsh: cd: too many arguments\n");
+		} else {
+			chdir(command[1]);
+			getcwd(pwd, sizeof(pwd)); 
+		}
+	} else if (!strcmp(command[0], "pwd")) {
+		printf("%s\n", pwd); 
+	} else {
+		status = execute(command, status); 
+	}
+	return status;
+}
+
+int main() {//int argc, char *argv[]) {
+	char *line = NULL;
+	size_t len = 0;
+	char** args;
+	int status = 0; // FIXME
+	int command_status = 0; // FIXME
+	getcwd(pwd, sizeof(pwd));
+	while(1) {
+		printf("orsh> "); // FIXME or TODO: add PS1 var
+		status = getline(&line, &len, stdin);
+		if (status == EOF) {
+			printf("\nexit\n");
+			break;
+		}
+		line[strlen(line) - 1] = '\0';
+		args = split_line(line);
+
+		command_status = parse_command(args);
+
+	}
+	return command_status;
+}