Add Rename A Bunch Of Files By Constructing mv Commands as a Unix TIL

README.md

@@ -10,7 +10,7 @@ pairing with smart people at Hashrocket.
 
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 - [Remove A Directory Called `-p`](unix/remove-a-directory-called-dash-p.md)
+- [Rename A Bunch Of Files By Constructing mv Commands](unix/rename-a-bunch-of-files-by-constructing-mv-commands.md)
 - [Repeat Yourself](unix/repeat-yourself.md)
 - [Replace Pattern Across Many Files In A Project](unix/replace-pattern-across-many-files-in-a-project.md)
 - [Run A Command Repeatedly Several Times](unix/run-a-command-repeatedly-several-times.md)

unix/rename-a-bunch-of-files-by-constructing-mv-commands.md

@@ -0,0 +1,51 @@
+# Rename A Bunch Of Files By Constructing mv Commands
+
+I downloaded a bunch of bank statements as PDFs. On the upside they all were
+consistently named. On the downside they used an unhelpful date format. With a
+date format that puts year before month before day, the files easily sort
+alphanumerically. However, these filenames used a date format that put month
+before day before year.
+
+Here is a subset of the files
+
+```bash
+$ ls *.pdf
+'012524 Statement.pdf'
+'012725 Statement.pdf'
+'022624 Statement.pdf'
+'022625 Statement.pdf'
+'032524 Statement.pdf'
+'032525 Statement.pdf'
+```
+
+Notice they are named with `MMDDYY Statement.pdf`. I would instead like for them
+to be named as `YYYY-MM-DD-statement.pdf`.
+
+I can generate a series of `mv` statements that then get piped to `sh` which
+_evaluates_ them. But first, let's do a dry run of a `sed` statement that
+rearranges the date parts.
+
+```bash
+$ ls *.pdf | sed 's/\(..\)\(..\)\(..\) Statement\.pdf/mv "&" "20\3-\1-\2-statement.pdf"/'
+mv "012524 Statement.pdf" "2024-01-25-statement.pdf"
+mv "012725 Statement.pdf" "2025-01-27-statement.pdf"
+mv "022624 Statement.pdf" "2024-02-26-statement.pdf"
+mv "022625 Statement.pdf" "2025-02-26-statement.pdf"
+mv "032524 Statement.pdf" "2024-03-25-statement.pdf"
+mv "032525 Statement.pdf" "2025-03-25-statement.pdf"
+```
+
+The way this works is that all the `pdf` files in the current directly get
+listed out. That gets piped to a `sed` statement that matches on capture groups
+against the first three pairs of characters (the date parts) in the filenames.
+It matches on the rest of the filename (` Statement.pdf`). This is then replaced
+by a `mv `, the full match of the original filename (`&`), and then the new
+filename made up of the rearranged date parts.
+
+I can then pipe it to `sh` to run those `mv` commands.
+
+```bash
+$ ls *.pdf |
+  sed 's/\(..\)\(..\)\(..\) Statement\.pdf/mv "&" "20\3-\1-\2-statement.pdf"/' |
+  sh
+```