ash: expr -e support

commands/ash/bltin/expr.c

@@ -279,6 +279,9 @@ expr_operator(op, sp, fs)
 	    sp->u.num = expr_is_false(sp);
 	    sp->type = BOOLEAN;
 	    break;
+      case EXISTS:
+	    if (fs->rcode >= 0) goto true;
+	    goto false;
       case ISREAD:
 	    i = 04;
 	    goto permission;

commands/ash/bltin/unary_op

@@ -5,6 +5,7 @@
 # by the Ash General Public License.  See the file named LICENSE.
 
 NOT	 !	3
+EXISTS	 -e	12   OP_FILE
 ISREAD	 -r	12   OP_FILE
 ISWRITE  -w	12   OP_FILE
 ISEXEC	 -x	12   OP_FILE

man/man1/expr.1

@@ -153,6 +153,8 @@ The remaining operators all deal with files.  Except as noted, they return
 false if the
 specified file does not exist.  The ones dealing with permission use
 the effective user and group ids of the shell.
+.u \-e string boolean
+True the file exists.
 .u \-r string boolean
 True if you have read permission on the file.
 .u \-w string boolean