Renaming a file in Bash using regular expressions

Question

I have a file named 35554842200284685106000166550020003504201637715423.xml and I simply need to rename it to 42200284685106000166550020003504201637715423.xml (remove everything before the last 48 characters). This simple regular expression (.{48}$) can extract the last 48 characters, but I can't make it work using rename in Bash.

How can I use rename and this regular expression to rename it to only the last 48 characters?

Edit:

Output of rename --help

[root@ip-000-00-0-000 tmp]# rename --help

Usage:
 rename [options] <expression> <replacement> <file>...

Rename files.

Options:
 -v, --verbose    explain what is being done
 -s, --symlink    act on the target of symlinks
 -n, --no-act     do not make any changes

 -h, --help     display this help and exit
 -V, --version  output version information and exit

For more details see rename(1).

Thank you.

Can you show us what you've tried, please. It also depends on the version of rename you're using - if you type rename just by itself what error message does it give you? — Chris Davies, Feb 24 '20 at 12:35
For example, rename 's/^.*(.{44}\.xml$)/$1/' 3*.xml works perfectly here — Chris Davies, Feb 24 '20 at 12:39
renames are legion. In different distros they may be differently... named. :) — Kamil Maciorowski, Feb 24 '20 at 12:43
I'm executing these commands on an AWS EC2 (Amazon Linux AMI) and executing the example sent by @roaima outputs a 'not enough arguments' error. Also, typing rename by itself also outputs 'not enough arguments'. — devegili, Feb 24 '20 at 12:52
Yep, that's the util-linux rename, you are looking for perl-rename or prename. By the way, please don't post images of text. Instead, paste the text directly into your question and use the formatting tools to format it as code. — terdon, Feb 24 '20 at 13:06
I wasn't aware that Bash used regular expressions for file operations. ??? — Bob Jarvis - Слава Україні, Feb 25 '20 at 23:04

score 18 · Accepted Answer · answered Feb 24 '20 at 13:05

You don't actually need rename here, you can work around it:

$ file=35554842200284685106000166550020003504201637715423.xml
$ newname=$(sed -E 's/.*(.{48})/\1/'<<<"$file"); 
$ mv -v "$file" "$newname"
renamed '35554842200284685106000166550020003504201637715423.xml' -> '42200284685106000166550020003504201637715423.xml'

Jetchisel · Answer 2 · 2021-11-01T05:17:39.523

15

Here is one using bash specific P.E. parameter expansion.

file=35554842200284685106000166550020003504201637715423.xml

Only mv for external tools

mv -v "$file" "${file:6}"

Output

renamed '35554842200284685106000166550020003504201637715423.xml' -> '42200284685106000166550020003504201637715423.xml'

Keeping the last 48 chars would be.

mv -v "$file" "${file:(-48)}"

edited Nov 01 '21 at 05:17

answered Feb 24 '20 at 13:16

Jetchisel

1,264

1

On my phone so can't test, but would ${file#??????} be a posix sh compatible alternative? – kojiro Feb 25 '20 at 12:00
@kojiro It is, tested on dash ash, ksh,zsh – Jetchisel Feb 25 '20 at 12:12
mksh,pdksh. it does not work however on *csh shell variants and fish. The thing is the OP wants to retain the last 48 chars. – Jetchisel Feb 25 '20 at 12:21

Stéphane Chazelas · Answer 3 · 2020-02-25T13:10:36.843

Your rename seems to be the useless one from util-linux.

You'd want to make sure one of the perl-based variants is installed instead (sometimes called prename) if you want to use regular expressions. And then:

rename -n 's:^\./\d+(?=\d{44}\.xml\Z)::' ./*.xml

(here replacing your 48 characters, with 44 digits followed by .xml so as to be more specific).

Alternatively, you could use zsh's zmv:

autoload zmv
zmv -n '[0-9]##([0-9](#c44).xml)' '$1'

Or

zmv -n '<->.xml~^?(#c48)' '$f[-48,-1]'

(remove -n (dry-run) to actually do it).

Which also has the benefit of guarding against conflicts (two files having the same destination name)

With bash, you could do something like:

shopt -s extglob nullglob
for f in +([[:digit:]]).xml; do
  ((${#f) <= 48)) || echo mv -i -- "$f" "${f: -48}"
done

I've also seen it called perl-rename and rename-perl – Mutantoe Feb 25 '20 at 12:31 — Mutantoe, Feb 25 '20 at 12:31

GAD3R · Answer 4 · 2020-02-24T13:37:06.510

2

file=35554842200284685106000166550020003504201637715423.xml
rename  "s/"$file"/"${file: -48}"/" *.xml

rename --version:

/usr/bin/rename using File::Rename version 1.10

edited Feb 24 '20 at 13:37

answered Feb 24 '20 at 13:26

GAD3R

66,769

Renaming a file in Bash using regular expressions

4 Answers4

Linked