Merge PDF files with pdftk

Having some of my manuals/documentations downloaded in several separated pdf files, I wanted to merge them into a single file.

First, I installed pdftk

# apt-get install pdftk

Then, I merged the files into a single file

$ pdftk file1.pdf file2.pdf file3.pdf cat output file123.pdf

When the files to be merged is a lot, I edited the file list in a text editor (or, when I am in a good mood, using ls & awk & sed) then combine it with the script found here

$ cat stdin_pdf.sh
#!/bin/sh
# combine PDFs; pass filenames in on stdin;
# pass output to stdout
read input_filenames
pdftk $input_filenames cat output -

$ cat filelist|./stdin_pdf.sh>mergedfile.pdf

So far, I am satisfied with the result.
However, I am still looking for the method to modify the hyperlink to suit the new file, since the previously scattered files actually hyperlinked to each other. RTFM is in progress :-)