Question for unix wizzards


#1

Dear devs,

2 small unix related questions.

does anyone know about:

  • a quick and easy way to remove duplicate lines from a text files?
  • a quick and easy way to decide if two image (binary) files are the
    same
    image/picture?

thanks in advance for your help!

-g.


#2

Hi,

  • a quick and easy way to remove duplicate lines from a text files?

cat file | sort | uniq > file

should work (if the sorting doesn’t matter in the file)

cat file | uniq > file

works if the duplicate lines are next to each other

  • a quick and easy way to decide if two image (binary) files are the same
    image/picture?

findimagedupes << search for that in google, I’m using one of those
perl scripts.

thanks in advance for your help!

Hope that helps,

Jo


#3

On Feb 4, 2008 5:09 PM, George M.
removed_email_address@domain.invalid wrote:

Dear devs,

2 small unix related questions.

does anyone know about:

  • a quick and easy way to remove duplicate lines from a text files?

uniq < filename (assuming that the lines are consequtive; otherwise,
you need to do a sort first, or keep the lines in a hash in either
Ruby or Perl)

  • a quick and easy way to decide if two image (binary) files are the same
    image/picture?

Do you mean if they are identical? cmp should do it. Another
approach is to get a checksum of the files (e.g. using "openssl rmd160
") and see if the checksum is the same.

Eivind.


#4

Thanks for the help everyone!


#5

On Mon, 2008-02-04 at 18:09 +0200, George M. wrote:

Dear devs,

2 small unix related questions.

does anyone know about:

delete duplicate, nonconsecutive lines from a file. Beware not to

overflow the buffer size of the hold space, or else use GNU sed.

sed -n ‘G; s/\n/&&/; /^([ -~]\n).\n\1/d; s/\n//; h; P’

  • a quick and easy way to decide if two image (binary) files are the
    same image/picture?
    diff will tell you if the files are different also

rthompso@raker ~ $ diff 10000_Galaxies,_HST_Ultra_Deep.png
Deathvalleysky_nps_big.png
Files 10000_Galaxies,_HST_Ultra_Deep.png and Deathvalleysky_nps_big.png
differ
rthompso@raker ~ $ cp 10000_Galaxies,_HST_Ultra_Deep.png junk.png
rthompso@raker ~ $ diff 10000_Galaxies,_HST_Ultra_Deep.png junk.png