commit 70ab6da52b9ca530d37e49e4ac35f5e24d6a2a1c
Author: Kamil Sowiński <kamsow@st.amu.edu.pl>
Date:   Mon Jul 9 22:03:45 2018 +0200

    Intial commit

diff --git a/Makefile b/Makefile
new file mode 100755
index 0000000..93fafcb
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,2 @@
+myshell: main.c
+	gcc -o myshell main.c -I .
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diff --git a/main.c b/main.c
new file mode 100755
index 0000000..4ed2b14
--- /dev/null
+++ b/main.c
@@ -0,0 +1,202 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <wait.h>
+
+// Removes new line from string
+char *remove_nl(char *p) {
+    char *nl = strchr( p, '\n' );
+    if (nl)
+        *nl = 0;
+    memset(nl, 0, sizeof nl);
+    return p;
+}
+
+// Checks for env variables in string and set them if found
+int set_evar(char *evar) {
+    char *end_evar;
+    char *value;
+    char *key;
+
+    key = strtok_r(evar, "=", &end_evar);
+    value = strtok_r(NULL, "=", &end_evar);
+
+    setenv(key, value, 1);
+
+    memset(evar, 0, sizeof evar);
+    memset(end_evar, 0, sizeof end_evar);
+    memset(key, 0, sizeof key);
+    memset(value, 0, sizeof value);
+
+    return 0;
+}
+
+// Displays basic shell prompt
+int display_prompt() {
+    char hostname[1024];
+    char cwd[1024];
+    char *username_p;
+
+    gethostname(hostname, 1024);
+    username_p = getenv("USER");
+    getcwd(cwd, 1024);
+
+    printf("[%s@%s %s] $ ", hostname, username_p, cwd);
+
+    // Flush memory
+    memset(hostname, 0, sizeof hostname);
+    memset(cwd, 0, sizeof cwd);
+
+    return 0;
+}
+
+// Commands
+int my_exit(char *param_list[64]) {
+    if (param_list[0] != NULL) {
+        exit( (int)strtol(param_list[0], NULL, 0) );
+    } else {
+        exit(0);
+    }
+}
+
+int my_cd(char *param_list[64]) {
+    if (param_list[0] != NULL) {
+        if (chdir(param_list[0]) == -1) {
+            printf("cd: %s: %s\n", param_list[0], strerror(errno));
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
+int my_kill(char *param_list[64]) {
+    if (param_list[0] != NULL) {
+        int process_pid = (int)strtol(param_list[0], NULL, 0);
+
+        if (process_pid > 0) {
+            if (kill(process_pid, SIGKILL) == -1) {
+                printf("kill: %s\n", strerror(errno));
+                memset(&process_pid, 0, sizeof process_pid);
+                return 1;
+            } else {
+                printf("kill: Killing process %d", process_pid);
+                memset(&process_pid, 0, sizeof process_pid);
+                return 0;
+            }
+        } else {
+            printf("kill: Invalid PID: %s\n" , param_list[0]);
+            memset(&process_pid, 0, sizeof process_pid);
+            return 1;
+        }
+    } else {
+        printf("Please specify PID\n");
+        return 1;
+    }
+}
+
+// Allows you to run subshell
+int my_myshell() {
+    pid_t child_pid;
+    child_pid = fork();
+
+    if (child_pid != 0) {
+        waitpid(child_pid, NULL, 0); //Wait for child
+    }
+}
+
+int main() {
+    char input[1024];
+    char *input_p;
+    char *param_p;
+    char *command_p;
+    char *param_list[64];
+    char evar[256];
+    pid_t child_pid;
+
+    while (1) {
+        evar[0] = '\0';
+        display_prompt();
+
+        fgets(input, 1024, stdin);
+
+        input_p = input;
+        input_p = remove_nl(input_p);
+
+        command_p = strtok(input_p, " ");
+
+        if (command_p != NULL) {
+            if (strchr(command_p, '=') != NULL) {
+                strcpy(evar, command_p);
+                command_p = strtok(NULL, " ");
+            }
+
+            if (!command_p || !command_p[0]) {
+                if (evar[0]  != '\0') {
+                    set_evar(evar);
+                }
+            } else {
+                param_p = strtok(NULL, " ");
+
+                int i = 0;
+                do {
+                    param_list[i] = param_p;
+                    param_p = strtok(NULL, " ");
+                    i=i+1;
+                } while(param_p != NULL);
+                memset(&i, 0, sizeof i);
+
+                if (strcmp(command_p, "exit") == 0) {
+                    my_exit(param_list);
+                } else if (strcmp(command_p, "cd") == 0) {
+                    my_cd(param_list);
+                } else if (strcmp(command_p, "kill") == 0)  {
+                    my_kill(param_list);
+                } else if (strcmp(command_p, "myshell") == 0) {
+                    my_myshell();
+                } else if (strcmp(command_p, "help") == 0) {
+                    printf(" MyShell is Bash-like shell written in C\n");
+                    printf(" Available commands: cd, kill, myshell, help, version, exit\n");
+                } else if (strcmp(command_p, "version") == 0) {
+                    printf(" Version: 0.0.1\n Author: Kamil Sowińśki\n");
+                } else {
+                    child_pid = fork();
+                    if (child_pid == 0) {
+                        char *args[66];
+                        int i = 1;
+                        int param_list_s = sizeof(param_list) / sizeof(param_list[0]);
+
+                        if (evar[0]  != '\0') {
+                            set_evar(evar);
+                        }
+
+                        args[0] = command_p;
+                        while (i < param_list_s) {
+                            args[i] = param_list[i - 1];
+                            i++;
+                        }
+                        args[i] = NULL;
+                        memset(&i, 0, sizeof i);
+
+                        if (execvp(command_p, args) == -1) {
+                            printf("%s: command not found\n", command_p);
+                            exit(1);
+                        }
+
+                        memset(args, 0, sizeof args);
+                    } else {
+                        waitpid(child_pid, NULL, 0); //Wait for child
+                    }
+                    memset(command_p, 0, sizeof command_p);
+                }
+            }
+        }
+
+        // Fush memory
+        memset(param_list, 0, sizeof param_list);
+        memset(input, 0, sizeof input);
+        memset(input_p, 0, sizeof input_p);
+    }
+}
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