how to remove alternate char from file

saurin · 01-14-2010, 04:18 PM

How to remove alternate char from file using shell script?
if the file content is "1234567890" the output file should be "24680"

there may be small modification to generate two alternate byte, what it should be?
if the file content is "1234567890" the output file should be "125689"

rweaver · 01-14-2010, 04:53 PM

It's not even really a script, just a simple one liner.

sed 's/\(.\)\(.\)/\2/g' filename

You could logic it out in bash I suppose using cut, but...

Code:

core:~/test/test26$ echo "1234567890" > filename
core:~/test/test26$ cat filename
1234567890
core:~/test/test26$ sed 's/\(.\)\(.\)/\2/g' filename
24680
core:~/test/test26$

I remember doing some fun things like this back in the 90s to make rudimentary document encryption with the addition of rotX (take each character of a document separate it by a space, fill the spaces with a random character, rotX the entire mess (with a special character set including basic punctuation.) Decryption was simple, could even do it in your head if you knew the trick, but at the time I was pretty impressed with my 'ingenuity'. Kept my programming teacher busy all year