One liner for filenames

Ruby
1

Hello,
Can someone help me to write a Ruby one-liner to remove all the files
except one in a list of files? I have a list of pages of an original
PDF. Each page has been converted to a PNG file. They’re each numbered
with an underscore and a number at their end.

filename_1.png
filename_2.png
filename_3.png
…

I need to basically delete all of the files except for the first one,
the one with the “_1” suffix at the end. Can I do that wiith a
one-liner?

Thanks,
Peter

2

Peter B. wrote in post #1091502:

Hello,
Can someone help me to write a Ruby one-liner to remove all the files
except one in a list of files? I have a list of pages of an original
PDF. Each page has been converted to a PNG file. They’re each numbered
with an underscore and a number at their end.

filename_1.png
filename_2.png
filename_3.png
…

I need to basically delete all of the files except for the first one,
the one with the “_1” suffix at the end. Can I do that wiith a
one-liner?

Thanks,
Peter

Test this:

ruby -e “Dir.foreach(‘C:/Directory_with_png/’) {|file| File.delete(file)
unless (file.==(’.’)) || (file.==(’…’) || (file.==(‘filename_1.png’))”

Kind regards.

3

I need to basically delete all of the files except for the first one,
the one with the “_1” suffix at the end. Can I do that wiith a
one-liner?

Thanks,
Peter

Hi,

This should work

ruby -e “Dir.glob(’_.png’)[1…-1].each { |fn| File.delete fn}”

Best regards
Kim

4

Kim P. wrote in post #1091524:

I need to basically delete all of the files except for the first one,
the one with the “_1” suffix at the end. Can I do that wiith a
one-liner?

Thanks,
Peter

Hi,

This should work

ruby -e “Dir.glob(’_.png’)[1…-1].each { |fn| File.delete fn}”

Best regards
Kim

Thank you very much, Kim. It’s a big help.
Cheers.

5

Robert K. wrote in post #1091597:

On Tue, Jan 8, 2013 at 9:48 PM, Peter B. [email protected]
wrote:

I need to basically delete all of the files except for the first one,
the one with the “_1” suffix at the end. Can I do that wiith a
one-liner?

ruby -r pathname -e ‘Pathname.glob(“*[^1].png”).each(&:delete)’

Kind regards

robert

Thanks, Robert.

6

Kim P. wrote in post #1091524:

I need to basically delete all of the files except for the first one,
the one with the “_1” suffix at the end. Can I do that wiith a
one-liner?

Thanks,
Peter

Hi,

This should work

ruby -e “Dir.glob(’_.png’)[1…-1].each { |fn| File.delete fn}”

Best regards
Kim

Kim,
I’d like to ask you about [1…-1]. I’ve never seen that before. Is that
what’s selecting all the files except the first one?
-Peter

7

On Tue, Jan 8, 2013 at 9:48 PM, Peter B. [email protected]
wrote:

I need to basically delete all of the files except for the first one,
the one with the “_1” suffix at the end. Can I do that wiith a
one-liner?

ruby -r pathname -e ‘Pathname.glob(“*[^1].png”).each(&:delete)’

Kind regards

robert

8

about Array#[]:

[1,2,3,4,5][1…-1] #=> [2,3,4,5]

about Dir.glob():

you need to be careful, because the array is unsorted

9

On Wed, Jan 9, 2013 at 4:48 PM, Jess Gabriel y Galn
[email protected] wrote:

On Wed, Jan 9, 2013 at 4:09 PM, Robert K.
[email protected] wrote:

ruby -r pathname -e ‘Pathname.glob(“*[^1].png”).each(&:delete)’

Careful, as this skips also filename_11.png, filename_21.png, etc.
Building on this:

ruby -r pathname -e ‘Pathname.glob(“*_{[^1],??}.png”).each(&:delete)’

+1 I wasn’t aware that there could be larger numbers. Thank you for
the correction!

Cheers

robert

10

“Jesús Gabriel y Galán” [email protected] wrote in post
#1091607:

On Wed, Jan 9, 2013 at 4:09 PM, Robert K.
[email protected] wrote:

…

I need to basically delete all of the files except for the first one,
the one with the “_1” suffix at the end. Can I do that wiith a
one-liner?

ruby -r pathname -e ‘Pathname.glob(“*[^1].png”).each(&:delete)’

Careful, as this skips also filename_11.png, filename_21.png, etc.
Building on this:

ruby -r pathname -e ‘Pathname.glob(“*_{[^1],??}.png”).each(&:delete)’

Jesus.

Excellent. Thanks. Hans is right, though. Dir.glob is unsorted. Is that
a problem here?

11

On Wed, Jan 9, 2013 at 5:00 PM, Peter B. [email protected]
wrote:

ruby -r pathname -e ‘Pathname.glob(“*[^1].png”).each(&:delete)’

Careful, as this skips also filename_11.png, filename_21.png, etc.
Building on this:

ruby -r pathname -e ‘Pathname.glob(“*_{[^1],??}.png”).each(&:delete)’

Jesus.

Excellent. Thanks. Hans is right, though. Dir.glob is unsorted. Is that
a problem here?

No, because here we are using the glob facility to do all the
filtering. In the other solution, there was the array returned from
the glob that was being filtered, and so the order was important for
the solution that removed the first entry in the array.

Jesus.

12

“Jesús Gabriel y Galán” [email protected] wrote in post
#1091613:

On Wed, Jan 9, 2013 at 5:00 PM, Peter B. [email protected]
wrote:

ruby -r pathname -e ‘Pathname.glob(“*[^1].png”).each(&:delete)’

Careful, as this skips also filename_11.png, filename_21.png, etc.
Building on this:

ruby -r pathname -e ‘Pathname.glob(“*_{[^1],??}.png”).each(&:delete)’

Jesus.

Excellent. Thanks. Hans is right, though. Dir.glob is unsorted. Is that
a problem here?

No, because here we are using the glob facility to do all the
filtering. In the other solution, there was the array returned from
the glob that was being filtered, and so the order was important for
the solution that removed the first entry in the array.

Jesus.

Beautiful. Thanks a lot.

13

On Wed, Jan 9, 2013 at 4:09 PM, Robert K.
[email protected] wrote:

…

I need to basically delete all of the files except for the first one,
the one with the “_1” suffix at the end. Can I do that wiith a
one-liner?

ruby -r pathname -e ‘Pathname.glob(“*[^1].png”).each(&:delete)’

Careful, as this skips also filename_11.png, filename_21.png, etc.
Building on this:

ruby -r pathname -e ‘Pathname.glob(“*_{[^1],??}.png”).each(&:delete)’

Jesus.

14

On Thu, Jan 10, 2013 at 1:09 AM, Peter B. [email protected]
wrote:

ruby -r pathname -e ‘Pathname.glob(“*_{[^1],??}.png”).each(&:delete)’

Jesus.

Beautiful. Thanks a lot.

This is what I’m getting. I’m sure i’m missing something simple.

ruby -r pathname -e ‘Pathname.glob(“*_{[^1],??}.png”).each(&:delete)’
-e:1: syntax error, unexpected $end, expecting ‘)’

Any chance you are using Ruby 1.8*? If so I suggest to upgrade to 1.9*.

Kind regards

robert

15

On 01/08/2013 05:04 PM, Damián M. González wrote:

…
ruby -e “Dir.foreach(‘C:/Directory_with_png/’) {|file| File.delete(file)
unless (file.==(’.’)) || (file.==(’…’) || (file.==(‘filename_1.png’))”

Kind regards.

There’s certainly many ways to do this, but globing will ignore the dot
dirs, and is a bit shorter.
File.delete Dir[’.png’].reject {|f| f =~ /_1.png$/ }

16

Peter B. wrote in post #1091614:

“Jesús Gabriel y Galán” [email protected] wrote in post
#1091613:

On Wed, Jan 9, 2013 at 5:00 PM, Peter B. [email protected]
wrote:

ruby -r pathname -e ‘Pathname.glob(“*[^1].png”).each(&:delete)’

Careful, as this skips also filename_11.png, filename_21.png, etc.
Building on this:

ruby -r pathname -e ‘Pathname.glob(“*_{[^1],??}.png”).each(&:delete)’

Jesus.

Excellent. Thanks. Hans is right, though. Dir.glob is unsorted. Is that
a problem here?

No, because here we are using the glob facility to do all the
filtering. In the other solution, there was the array returned from
the glob that was being filtered, and so the order was important for
the solution that removed the first entry in the array.

Jesus.

Beautiful. Thanks a lot.

This is what I’m getting. I’m sure i’m missing something simple.

ruby -r pathname -e ‘Pathname.glob(“*_{[^1],??}.png”).each(&:delete)’
-e:1: syntax error, unexpected $end, expecting ‘)’

17

On 01/10/2013 06:58 AM, Peter B. wrote:

dirs, and is a bit shorter.
File.delete Dir[’.png’].reject {|f| f =~ /_1.png$/ }

Thanks, Brian. But, even preceding this with “ruby -e” gives me nothing.
Should I make this part of a script instead of it being a one-liner?

That’s odd… Works for me under 1.8.7, 1.9.2 and 1.9.3.
ruby -e “File.delete Dir[’.png’].reject {|f| f=~ /_1.png$/ }”
There will be no output. It will just delete the files.

18

Brian D. B. wrote in post #1091712:

On 01/08/2013 05:04 PM, Damián M. González wrote:

…
ruby -e “Dir.foreach(‘C:/Directory_with_png/’) {|file| File.delete(file)
unless (file.==(’.’)) || (file.==(’…’) || (file.==(‘filename_1.png’))”

Kind regards.

There’s certainly many ways to do this, but globing will ignore the dot
dirs, and is a bit shorter.
File.delete Dir[’.png’].reject {|f| f =~ /_1.png$/ }

Thanks, Brian. But, even preceding this with “ruby -e” gives me nothing.
Should I make this part of a script instead of it being a one-liner?