How to Batch Rename Files in a macOS Terminal? - bash

Question

I have a folder with a series of files named:
prefix_1234_567.png
prefix_abcd_efg.png
I'd like to batch remove one underscore and the middle content so the output would be:
prefix_567.png
prefix_efg.png
Relevant but not completely explanatory:
How can I batch rename files using the Terminal?
Regex to batch rename files in OS X Terminal

Answer 1

In your specific case you can use the following bash command (bash is the default shell on macOS):
for f in *.png; do echo mv "$f" "${f/_*_/_}"; done
Note: If there's a chance that your filenames start with -, place -- before them[1]:
mv -- "$f" "${f/_*_/_}"
Note: echo is prepended to mv so as to perform a dry run. Remove it to perform actual renaming.
You can run it from the command line or use it in a script.
"${f/_*_/_}" is an application of bash parameter expansion: the (first) substring matching pattern _*_ is replaced with literal _, effectively cutting the middle token from the name.
Note that _*_ is a pattern (a wildcard expression, as also used for globbing), not a regular expression (to learn about patterns, run man bash and search for Pattern Matching).
If you find yourself batch-renaming files frequently, consider installing a specialized tool such as the Perl-based rename utility.
On macOS you can install it using popular package manager Homebrew as follows:
brew install rename
Here's the equivalent of the command at the top using rename:
rename -n -e 's/_.*_/_/' *.png
Again, this command performs a dry run; remove -n to perform actual renaming.
Similar to the bash solution, s/.../.../ performs text substitution, but - unlike in bash - true regular expressions are used.
[1] The purpose of special argument --, which is supported by most utilities, is to signal that subsequent arguments should be treated as operands (values), even if they look like options due to starting with -, as Jacob C. notes.

Answer 2

To rename files, you can use the rename utility:
brew install rename
For example, to change a search string in all filenames in current directory:
rename -nvs searchword replaceword *
Remove the 'n' parameter to apply the changes.
More info: man rename

Answer 3

You could use sed:
ls * | sed -e 'p;s#_.*_#_#g' | xargs -n2 mv
result:
prefix_567.png prefix_efg.png
*to do a dry-run first, replace mv at the end with echo
Explanation:
e: optional for only 1 sed command.
p: to print the input to sed, in this case it will be the original file name before any renaming
#: is a replacement of / character to make sed more readable. That is, instead of using sed s/search/replace/g, use s#search#replace#g
_.* : the underscore is an escape character to refer to the actual '.' character zero or more times (as opposed to ANY character in regex)
-n2: indicates that there are 2 outputs that need to be passed on to mv as parameters. for each input from ls, this sed command will generate 2 output, which will then supplied to mv.

Answer 4

I had a batch of files that looked like this: be90-01.png and needed to change the dash to underscore. I used this, which worked well:
for f in *; do mv "$f" "`echo $f | tr '-' '_'`"; done

Answer 5

you can install rename command by using brew. just do brew install rename and use it.

Answer 6

Using mmv
mmv '*_*_*' '#1_#3' *.png

Answer 7

try this
for i in *.png ; do mv "$i" "${i/remove_me*.png/.png}" ; done
Here is another way:
for file in Name*.png; do mv "$file" "01_$file"; done

Answer 8

Since programmatically renaming files is risky (potentially destructive if you get it wrong), I would use a tool with a dry run mode built specifically for bulk renaming, e.g. renamer.
This command operates on all files in the current directory, use --dry-run until you're confident the output looks correct:
$ renamer --find "/(prefix_)(\w+_)(\w+)/" --replace "$1$3" -e name --dry-run *
Dry run
✔︎ prefix_1234_567.png → prefix_567.png
✔︎ prefix_abcd_efg.png → prefix_efg.png
Rename complete: 2 of 2 files renamed.
Plenty more renamer usage examples here.