{"id":105439,"date":"2021-07-14T07:00:00","date_gmt":"2021-07-14T14:00:00","guid":{"rendered":"https:\/\/devblogs.microsoft.com\/oldnewthing\/?p=105439"},"modified":"2021-07-14T07:06:02","modified_gmt":"2021-07-14T14:06:02","slug":"20210714-00","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/oldnewthing\/20210714-00\/?p=105439","title":{"rendered":"How to perform more complicated search and replace-style renaming in a batch file"},"content":{"rendered":"

Last time, we looked at how copying and renaming with wildcards worked in MS-DOS<\/a>, and how it doesn’t work well if you are trying to perform search-and-replace operations where the strings have different lengths.<\/p>\n

For example, if you have a list of files, say fred001.txt<\/tt> through fred999.txt<\/tt> and you want to rename them to wilma001.txt<\/tt> through wilma999.txt<\/tt>, the obvious command<\/p>\n

ren fred*.txt wilma*.txt\r\n<\/pre>\n
will not produce the desired results because the a<\/tt> in wilma<\/tt> overwrites the first character that was matched by the wildcard in the source pattern, since fred<\/tt> is only four characters long.<\/p>\n
You can still get what you want; you just won’t be able to use the wildcard algorithm to do it.<\/p>\n
setlocal enabledelayedexpansion\r\nfor %%i in (fred*.txt) do set \"_=%%i\" & ren \"%%i\" \"!_:fred=wilma!\"\r\n<\/pre>\n
We write a little batch file to perform the bulk rename operation.<\/p>\n
The main loop is driven by the FOR<\/code> command, which we ask to enumerate all the files that match the pattern fred*.txt<\/tt>. For each such file, we set the variable _<\/tt> to the file name. I like to use _<\/tt> as a scratch variable name in batch files because it’s unlikely to collide with a name that means something to any particular program.\u00b9<\/p>\n
We then perform a non-wildcard ren<\/code> command. The source file name is the file name which the FOR<\/code> command gave us. The destination file name is the result of a search-replace operation with the _<\/tt> variable, where we ask to search for fred<\/tt> and change it to wilma<\/tt>.<\/p>\n
This is a two-liner instead of a one-liner because we need to enable delayed expansion so that we can delay the search-replace operation until after the _<\/tt> variable is set.<\/p>\n
If I need to do some sort of fancy renaming, I don’t do any of this. I’ll do a dir \/b<\/code> and dump the list of file names into a file. Then I’ll edit that file and use the editor’s fancy search-replace features to convert it into a list of REN<\/code> commands. I’ll look over the results to verify that they are doing what I want, and possibly perform some editing to deal with special cases like “Don’t rename fred314.txt<\/tt>; that one stays unchanged.” Once I’m satisfied, I save the results as a batch file and run it.<\/p>\n
If the editing is particularly complicated, I’ll write a one-off program to generate the batch file. I prefer generating a batch file to having the one-off program perform the renames directly, because that lets me preview the operation. You don’t want to mess it up.<\/p>\n
Bonus chatter<\/b>: The reimagined  Windows PowerToys<\/a> includes an interactive bulk renaming tool called  PowerRename<\/a>.<\/p>\n
\u00b9 Sometimes people new to batch programming will have need for a temporary variable to hold a path, and they call it PATH<\/tt>. This tends to result in a lot of head-scratching, since they are unwittingly modifying the executable search path.<\/p>\n","protected":false},"excerpt":{"rendered":"
Try something other than wildcards.<\/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":[25],"class_list":["post-105439","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-oldnewthing","tag-code"],"acf":[],"blog_post_summary":"
Try something other than wildcards.<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/105439","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=105439"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/posts\/105439\/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=105439"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/categories?post=105439"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/oldnewthing\/wp-json\/wp\/v2\/tags?post=105439"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}