$ echo "hello" > toto
$ cat toto
hello
$ perl -e 'open F, "<toto"; sleep 30; print <F>'


##</code><code>##

$ perl -e 'open F, ">toto"; print F 'goodbye'; close F; sleep 30'

##</code><code>##

perl -e 'open F, ">toto"; system ("mv toto tata"); print F 'goodbye'; close F; sleep 30'

##</code><code>##

perl -e 'open F, ">toto"; system ("mv toto tata"); print F 'goodbye'; sleep 30'