Using sort (GNU coreutils) 8.4 ... 

sh
sort -u -t '~' file-1 file-2 file-3 file-4 > x \
&& mv -f x file-1

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In reply to Re: How can I merge a number of text files into one in a particular sequence? by Anonymous Monk
in thread How can I merge a number of text files into one in a particular sequence? by SamSmith

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