{"id":44924,"date":"2015-05-06T07:00:00","date_gmt":"2015-05-06T21:00:00","guid":{"rendered":"https:\/\/blogs.msdn.microsoft.com\/oldnewthing\/2015\/05\/06\/why-is-there-an-invisible-u202a-at-the-start-of-my-file-name\/"},"modified":"2019-03-13T12:15:16","modified_gmt":"2019-03-13T19:15:16","slug":"20150506-00","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/oldnewthing\/20150506-00\/?p=44924","title":{"rendered":"Why is there an invisible U+202A at the start of my file name?"},"content":{"rendered":"

There’s something strange about this property sheet page: <\/p>\n\n\n
<\/span><\/td>\n\n\n\n\n
<\/span><\/td>\n IMG31415 Properties <\/td>\n ×<\/b> <\/span> <\/td>\n<\/tr>\n<\/table>\n<\/td>\n<\/span><\/td>\n<\/tr>\n
<\/span><\/td>\n\n\n\n\n
\n
General <\/div>\n<\/td>\n
\n
Security <\/div>\n<\/td>\n
\n
Details <\/div>\n<\/td>\n
   <\/td>\n<\/tr>\n
\n
Object name:       C:\\Users\\Bob\\Desktop\\IMG31415.jpg <\/div>\n
Group or user names: <\/div>\n\n\n\n\n\n\n\n
👤<\/span>  👤<\/span> <\/td>\n SYSTEM <\/td>\n<\/tr>\n
 👤 <\/td>\n Bob <\/td>\n<\/tr>\n
👤<\/span>  👤<\/span> <\/td>\n Administrators <\/td>\n<\/tr>\n
 <\/td>\n<\/tr>\n
 <\/td>\n<\/tr>\n
 <\/td>\n<\/tr>\n<\/table>\n
To change permissions, click Edit. Edit…<\/span> <\/div>\n\n\n\n\n\n\n\n\n\n\n\n\n\n
Permissions for SYSTEM<\/td>\nAllow<\/td>\nDeny<\/td>\n<\/tr>\n<\/thead>\n
Full control<\/td>\n ✓<\/td>\n  <\/td>\n<\/tr>\n
Modify<\/td>\n ✓<\/td>\n  <\/td>\n<\/tr>\n
Read & execute<\/td>\n ✓<\/td>\n  <\/td>\n<\/tr>\n
Read<\/td>\n ✓<\/td>\n  <\/td>\n<\/tr>\n
Write<\/td>\n ✓<\/td>\n  <\/td>\n<\/tr>\n
Special permissions<\/td>\n  <\/td>\n  <\/td>\n<\/tr>\n
 <\/td>\n  <\/td>\n  <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
Advanced…<\/span> For special permissions or advanced settings, click Advanced. <\/div>\n<\/td>\n<\/tr>\n<\/table>\n<\/td>\n
<\/span><\/td>\n<\/tr>\n
<\/span><\/td>\n Apply<\/span> Cancel<\/span> OK<\/span> <\/td>\n<\/span><\/td>\n<\/tr>\n
<\/span><\/td>\n<\/tr>\n<\/table>\n

Okay, that was a trick question, because the thing that’s strange is not visible to the eye. <\/p>\n

Use the mouse to click in the object name field (the thing with the file path), then press Home<\/kbd>, followed by Shift<\/kbd>+End<\/kbd> to select the entire text, then Ctrl<\/kbd>+C<\/kbd> to copy it to the clipboard. <\/p>\n

Now things get interesting. <\/p>\n

Fire up Notepad, paste the path into the Notepad document, and save it to the desktop with the name tricky.txt<\/tt>. <\/p>\n

Huh? Notepad says, “This file contains characters in Unicode format which will be lost if you save this as an ANSI encoded text file.” <\/p>\n

What Unicode characters are we talking about? There are no accented letters here. All the characters in the file name fit in the ASCII repertoire. <\/p>\n

Go to a command prompt and type <\/p>\n

\nC:\\Users\\Bob> copy \"\n<\/pre>\n
and then paste the path from the clipboard, then close the quotation mark, and hit Enter. <\/p>\n
\nC:\\Users\\Bob> copy \"?C:\\Users\\Bob\\Desktop\\IMG31415.jpg\"\nThe filename, directory name, or volume label syntax is incorrect.\n<\/pre>\n
Wait, what? Where did that rogue question mark come from? <\/p>\n
The answers to the two questions are the same: The mysterious Unicode character, which is invisible in Notepad, and which appears as a question mark on the command line, is U+202A (LEFT-TO-RIGHT EMBEDDING). <\/p>\n
We saw some time ago<\/a> that you can, as a last resort, insert the character U+202B (RIGHT-TO-LEFT EMBEDDING) to force text to be interpreted as right-to-left. The converse character is U+202A (LEFT-TO-RIGHT EMBEDDING), which forces text to be interpreted as left-to-right. <\/p>\n
The Security dialog box inserts that control character in the file name field in order to ensure that the path components are interpreted in the expected manner<\/a>. Unfortunately, it also means that if you try to copy the text out of the dialog box, the Unicode formatting control character comes along for a ride. Since the character is normally invisible, it can create all sorts of silent confusion. <\/p>\n
(We’re lucky that the confusion was quickly detected by Notepad and the command prompt. But imagine if you had pasted the path into the source code to a C program!) <\/p>\n","protected":false},"excerpt":{"rendered":"
The desperation Left-to-right marker.<\/p>\n","protected":false},"author":1069,"featured_media":111744,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1],"tags":[104],"class_list":["post-44924","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-tipssupport"],"acf":[],"blog_post_summary":"
The desperation Left-to-right marker.<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/44924","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/users\/1069"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/comments?post=44924"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/44924\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media\/111744"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/media?parent=44924"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=44924"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=44924"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}