You can use sed with something like
sed '1 s/^.*$/<?php/'
The 1 part only replaces the first line. Then, thanks to the s command, it replaces the whole line by <?php.
To modify your files in-place, use the -i option of GNU sed.
You can use sed with something like
sed '1 s/^.*$/<?php/'
The 1 part only replaces the first line. Then, thanks to the s command, it replaces the whole line by <?php.
To modify your files in-place, use the -i option of GNU sed.