However you still can get the same functionality on Linux using "xsel" command! But you need some modification to make it works as same as pb tools.
Just edit your ".bashrc" file and add:
alias pbcopy='xsel --clipboard --input' alias pbpaste='xsel --clipboard --output'
Once you did, you can use them just like original ones. e.g. if you want to copy a content of file:
cat /etc/fstab | pbcopy
And if you want to past what you have currently in your clipboard, just use pbpaste!
Now enjoy your Linux system! It's the best system as you know :-)