To enable this, there are 2 packages that you need to install, which are cups and cups-pdf. This has been tested on CentOS 5.5.
# yum install cups cups-pdf -y
Once installed, check which printer is available:
$ lpstat -p -d printer Cups-PDF is idle. enabled since Wed 10 Jul 2013 09:30:05 AM EST no system default destination
where lpstat is to show cups status information, -p is to tell lpstat to list all printers available and -d is to show the current default destination. In this case, this system has one printer installed, which is Cups-PDF.
To print, lpr command is needed:
$ echo "Printing some characters to a pdf file" | lpr -P Cups-PDF -J print01.pdf
where -P is to specify the printer name that you want to use, and -J is for the output file name.
The file will be saved in ~/Desktop, but this can be changed in /etc/cups/cups-pdf.conf.
$ ls ~/Desktop/ print01.pdf