diff --git a/src/execution/execution.c b/src/execution/execution.c
index 855fd37..0066681 100644
--- a/src/execution/execution.c
+++ b/src/execution/execution.c
@@ -12,14 +12,14 @@
  * @brief converts a linked list of command arguments to an argv array. Don't
  * forget to free the result
  *
- * @param cmd_list Linked list of command arguments
+ * @param command_list Linked list of command arguments
  * @return char** Array of command arguments suitable for execvp. Terminated by
  * NULL
  */
-static char **list_to_argv(struct list *cmd_list)
+static char **list_to_argv(struct list *command_list)
 {
     size_t len = 0;
-    struct list *cur = cmd_list;
+    struct list *cur = command_list;
 
     while (cur)
     {
@@ -32,7 +32,7 @@ static char **list_to_argv(struct list *cmd_list)
     {
         return NULL;
     }
-    cur = cmd_list;
+    cur = command_list;
 
     for (size_t i = 0; i < len; i++)
     {
@@ -45,19 +45,19 @@ static char **list_to_argv(struct list *cmd_list)
 }
 
 /**
- * @brief Executes a command represented by an ast_cmd structure
+ * @brief Executes a command represented by an ast_command structure
  *
- * @param cmd The command to execute
+ * @param command The command to execute
  * @return int The exit status of the command
  */
-static int exec_command(struct ast_cmd *cmd)
+static int exec_command(struct ast_command *command)
 {
-    if (!cmd || !(cmd->cmd))
+    if (!command || !(command->command))
     {
         return -1;
     }
 
-    char **argv = list_to_argv(cmd->cmd);
+    char **argv = list_to_argv(command->command);
 
     if (!argv || !(argv[0]))
     {
@@ -112,8 +112,8 @@ int execution(struct ast *ast)
         return 0;
     }
     case AST_CMD: {
-        struct ast_cmd *cmd = ast_get_cmd(ast);
-        return exec_command(cmd); // It's recursive
+        struct ast_command *command = ast_get_command(ast);
+        return exec_command(command); // It's recursive
     }
     case AST_IF: {
         struct ast_if *if_node = ast_get_if(ast);
diff --git a/src/expansion/expansion.c b/src/expansion/expansion.c
index 406c00b..fe28dd0 100644
--- a/src/expansion/expansion.c
+++ b/src/expansion/expansion.c
@@ -14,15 +14,15 @@
 //     return iter - start;
 // }
 
-struct ast_cmd *expand(struct ast_cmd *cmd)
+struct ast_command *expand(struct ast_command *command)
 {
-    if (cmd == NULL)
+    if (command == NULL)
         return NULL;
 
     bool in_quotes = false;
     char *str;
     size_t len;
-    struct list *l = cmd->cmd;
+    struct list *l = command->command;
 
     while (l != NULL)
     {
@@ -69,19 +69,19 @@ struct ast_cmd *expand(struct ast_cmd *cmd)
 
         l = l->next;
     }
-    return cmd;
+    return command;
 }
 
 // int main()
 // {
 //     printf("Expansion module test\n");
-//     struct ast_cmd ast_cmd;
+//     struct ast_command ast_command;
 //     // char str[] = "echo Hello $?";
 //     char str[] = "echo Hello $AE86";
-//     ast_cmd.cmd = list_append(NULL, str);
+//     ast_command.command = list_append(NULL, str);
 
-//     struct ast_cmd *cmd2 = expand(&ast_cmd);
-//     printf("cmd2: %s\n", (char *)cmd2->cmd->data);
+//     struct ast_command *command2 = expand(&ast_command);
+//     printf("command2: %s\n", (char *)command2->command->data);
 
 //     return 0;
 // }
diff --git a/src/io_backend/io_backend.c b/src/io_backend/io_backend.c
index eef080a..c3c38e3 100644
--- a/src/io_backend/io_backend.c
+++ b/src/io_backend/io_backend.c
@@ -42,7 +42,7 @@ int iob_init(struct iob_context *ctx)
         return 0;
 
     case IOB_MODE_CMD:
-        if (context.args != NULL)
+        if (context.args == NULL)
             return IOB_ERROR_BAD_ARG;
         state = IOB_STATE_READY;
         return 0;
@@ -121,7 +121,7 @@ int iob_config_from_args(struct args_options *args, struct iob_context *ctx)
 
     case INPUT_CMD:
         ctx->mode = IOB_MODE_CMD;
-        ctx->args = NULL;
+        ctx->args = (char *)args->input_source;
         break;
 
     default:
diff --git a/src/utils/ast/ast.c b/src/utils/ast/ast.c
index e04e170..2d0ce84 100644
--- a/src/utils/ast/ast.c
+++ b/src/utils/ast/ast.c
@@ -2,25 +2,26 @@
 
 #include <stdbool.h>
 
-void ast_free(struct ast *node)
+void ast_free(struct ast **node)
 {
-    if (node == NULL)
+    if (*node == NULL)
         return;
     // ast void does not need to be freed.
-    if (ast_is_if(node))
-        ast_free_if(ast_get_if(node));
-    else if (ast_is_command(node))
-        ast_free_command(ast_get_command(node));
-    else if (ast_is_list(node))
-        ast_free_list(ast_get_list(node));
+    if (ast_is_if(*node))
+        ast_free_if(ast_get_if(*node));
+    else if (ast_is_command(*node))
+        ast_free_command(ast_get_command(*node));
+    else if (ast_is_list(*node))
+        ast_free_list(ast_get_list(*node));
 
-    free(node);
+    free(*node);
+    *node = NULL;
 }
 
 struct ast *ast_create(enum ast_type type, void *data)
 {
     struct ast *node = malloc(sizeof(struct ast));
-    if (!node)
+    if (node == NULL)
         return NULL;
 
     node->type = type;
diff --git a/src/utils/ast/ast.h b/src/utils/ast/ast.h
index 79eeff3..8ac85a0 100644
--- a/src/utils/ast/ast.h
+++ b/src/utils/ast/ast.h
@@ -7,15 +7,4 @@
 #include "utils/ast/ast_list.h"
 #include "utils/ast/ast_void.h"
 
-/* @brief: returns an ast* with corresponding data and type.
- *
- * @note: this function should only be called by ast_create_[TYPE] functions.
- */
-struct ast *ast_create(enum ast_type type, void *data);
-
-/* @brief: frees the given ast. If ast is NULL, does nothing.
- *
- */
-void ast_free(struct ast *node);
-
 #endif /* ! AST_H */
diff --git a/src/utils/ast/ast_base.h b/src/utils/ast/ast_base.h
index 955ccdc..432eb2c 100644
--- a/src/utils/ast/ast_base.h
+++ b/src/utils/ast/ast_base.h
@@ -8,6 +8,7 @@ enum ast_type
     AST_END,
     AST_LIST,
     AST_IF,
+    AST_VOID,
     AST_CMD
 };
 
@@ -24,4 +25,15 @@ struct ast
     void *data;
 };
 
+/* @brief: returns an ast* with corresponding data and type.
+ *
+ * @note: this function should only be called by ast_create_[TYPE] functions.
+ */
+struct ast *ast_create(enum ast_type type, void *data);
+
+/* @brief: frees the given ast. If ast is NULL, does nothing.
+ *
+ */
+void ast_free(struct ast **node);
+
 #endif /* ! AST_BASE_H */
diff --git a/src/utils/ast/ast_command.c b/src/utils/ast/ast_command.c
index 6ad8fcc..920b1ff 100644
--- a/src/utils/ast/ast_command.c
+++ b/src/utils/ast/ast_command.c
@@ -30,9 +30,10 @@ bool ast_is_command(struct ast *node)
     return node->type == AST_CMD;
 }
 
-void ast_free_command(struct ast_command **command_data)
+void ast_free_command(struct ast_command *command_data)
 {
-    list_deep_destroy((*command_data)->command);
-    free(*command_data);
-    *command_data = NULL;
+    if (command_data == NULL)
+        return;
+    list_deep_destroy(command_data->command);
+    free(command_data);
 }
diff --git a/src/utils/ast/ast_command.h b/src/utils/ast/ast_command.h
index 0e442a5..08c62ba 100644
--- a/src/utils/ast/ast_command.h
+++ b/src/utils/ast/ast_command.h
@@ -30,6 +30,6 @@ struct ast *ast_create_command(struct list *command);
 /*
  * @brief: frees the given ast_command and sets the pointer to NULL.
  */
-void ast_free_command(struct ast_command **command_data);
+void ast_free_command(struct ast_command *command_data);
 
 #endif /* ! AST_COMMAND_H */
diff --git a/src/utils/ast/ast_if.c b/src/utils/ast/ast_if.c
index 242d5fd..6a25a9c 100644
--- a/src/utils/ast/ast_if.c
+++ b/src/utils/ast/ast_if.c
@@ -31,15 +31,14 @@ bool ast_is_if(struct ast *node)
     return node->type == AST_IF;
 }
 
-void ast_free_if(struct ast_if **if_data)
+void ast_free_if(struct ast_if *if_data)
 {
-    if (if_data == NULL || *if_data == NULL)
+    if (if_data == NULL)
         return;
 
-    ast_free((*if_data)->condition);
-    ast_free((*if_data)->then_clause);
-    ast_free((*if_data)->else_clause);
+    ast_free(&if_data->condition);
+    ast_free(&if_data->then_clause);
+    ast_free(&if_data->else_clause);
 
-    free(*if_data);
-    *if_data = NULL;
+    free(if_data);
 }
diff --git a/src/utils/ast/ast_if.h b/src/utils/ast/ast_if.h
index 2036eb7..51c1844 100644
--- a/src/utils/ast/ast_if.h
+++ b/src/utils/ast/ast_if.h
@@ -31,6 +31,6 @@ struct ast *ast_create_if(struct ast *condition, struct ast *then_clause,
 /*
  * @brief: frees the given ast_if and sets the pointer to NULL.
  */
-void ast_free_if(struct ast_if **if_data);
+void ast_free_if(struct ast_if *if_data);
 
 #endif /* ! AST_IF_H */
diff --git a/src/utils/ast/ast_list.c b/src/utils/ast/ast_list.c
index fae1f1a..95e7047 100644
--- a/src/utils/ast/ast_list.c
+++ b/src/utils/ast/ast_list.c
@@ -1,12 +1,14 @@
 #include "utils/ast/ast.h"
 
+#include <assert.h>
+
 struct ast *ast_create_list(struct list *list)
 {
     struct ast_list *ast_list = malloc(sizeof(struct ast_list));
     if (ast_list == NULL)
         return NULL;
 
-    ast_list->list = list;
+    ast_list->children = list;
 
     return ast_create(AST_LIST, ast_list);
 }
@@ -22,12 +24,25 @@ bool ast_is_list(struct ast *node)
     return node->type == AST_LIST;
 }
 
-void ast_free_list(struct ast_list **ast_list)
+void ast_free_list(struct ast_list *ast_list)
 {
-    if (*ast_list == NULL || ast_list == NULL)
+    if (ast_list == NULL)
         return;
 
-    list_deep_destroy((*ast_list)->children);
-    free(*ast_list);
-    *ast_list = NULL;
+    list_deep_destroy(ast_list->children);
+    free(ast_list);
+}
+
+void ast_list_deep_destroy(struct list *l)
+{
+    struct list *elt = l;
+    struct list *next_elt;
+    while (elt != NULL)
+    {
+        next_elt = elt->next;
+
+        ast_free(elt->data);
+        free(elt);
+        elt = next_elt;
+    }
 }
diff --git a/src/utils/ast/ast_list.h b/src/utils/ast/ast_list.h
index 6f1cbd9..591b045 100644
--- a/src/utils/ast/ast_list.h
+++ b/src/utils/ast/ast_list.h
@@ -11,6 +11,14 @@ struct ast_list
     struct list *children; // A list of ASTs (ast*)
 };
 
+/*
+** Release the memory used by the AST list and its AST children
+** Does nothing if `list` is `NULL`.
+*
+* @warning: this function should NEVER be used on a list containing
+*       anything else than ASTs.
+*/
+void ast_list_deep_destroy(struct list *l);
 
 /**
  * Creates a new AST node representing a list of ASTs