add: echo

src/env.c

@@ -10,7 +10,7 @@ env *init_envs() {
   envs[0].value = "/";
 
   envs[1].key = "USER";
-  envs[1].value = "guams";
+  envs[1].value = "iatic";
 
   envs[2].key = "HOST";
   envs[2].value = "tartempion";

src/exec.c

@@ -31,15 +31,71 @@ int do_cd(disk *d, char *path) {
   return 1;
 }
 
+#include "env.h"
+#include <ctype.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+int do_echo(char **args) {
+  if (args[0] == NULL) {
+    printf("\n");
+    return 1;
+  }
+
+  char result[4096] = {0};
+  int pos = 0;
+
+  for (int i = 0; args[i] != NULL; i++) {
+    char *word = args[i];
+
+    for (int j = 0; word[j] != '\0'; j++) {
+      if (word[j] == '$' && word[j + 1] != '\0') {
+        j++;
+        int start = j;
+
+        while (word[j] != '\0' && (isalnum(word[j]) || word[j] == '_')) {
+          j++;
+        }
+
+        int len = j - start;
+        if (len > 0) {
+          char key[64];
+          strncpy(key, &word[start], len);
+          key[len] = '\0';
+
+          char *val = get_env_value(key);
+          if (val != NULL) {
+            int val_len = strlen(val);
+            strcpy(&result[pos], val);
+            pos += val_len;
+          }
+        }
+        j--;
+      } else {
+        result[pos++] = word[j];
+      }
+    }
+
+    if (args[i + 1] != NULL) {
+      result[pos++] = ' ';
+    }
+  }
+
+  result[pos] = '\0';
+  printf("%s\n", result);
+  return 1;
+}
+
 int child_process_job(disk *d, char **args) {
   if (strcmp("ls", args[0]) == 0) {
-    do_ls(d, args[1]);
+    return do_ls(d, args[1]);
   } else if (strcmp("mkdir", args[0]) == 0) {
-    do_mkdir(d, args[1]);
+    return do_mkdir(d, args[1]);
   } else if (strcmp("touch", args[0]) == 0) {
-    do_touch(d, args[1]);
+    return do_touch(d, args[1]);
   } else if (strcmp("df", args[0]) == 0) {
-    do_df(d);
+    return do_df(d);
   } else {
     dprintf(STDERR_FILENO, "%s: no such command\n", args[0]);
   }
@@ -49,6 +105,8 @@ int child_process_job(disk *d, char **args) {
 int execute_cmd(disk *d, char **args) {
   if (strcmp(args[0], "cd") == 0) {
     return do_cd(d, args[1]);
+  } else if (strcmp(args[0], "echo") == 0) {
+    return do_echo(&args[1]);
   }
 
   int pid = fork();
@@ -58,7 +116,7 @@ int execute_cmd(disk *d, char **args) {
   }
 
   if (pid == 0) {
-    child_process_job(d, args);
+    return child_process_job(d, args);
   } else {
     int status;
     waitpid(pid, &status, WUNTRACED);

src/exec.h

@@ -11,6 +11,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/wait.h>
+#include <ctype.h>
 
 int is_builtin_cmd(char *executable);
 int execute_cmd(disk *d, char **args);