How to copy on clipboard for Linux-Ubuntu

Ubuntu14.04 can't use `pbcopy` command.
However, there is an alternative way.
The command is `xsel`.
The command `xsel` needs `--clipboard` and `--input` as options.

xsel --clipboard --input

can copy on clipboard.
I can replace `xsel --clipboard --input` with `pbcopy`.
In particular, I use `alias` command.

alias pbcopy='xsel --clipboard --input'

I can hereby use as `pbcopy` command.