My setup: TeX Live, version 2014.20141024-2 (packaged with Debian 8 Jessie)
man tex it's written:
... when called as tex the tex format is used, which is identical to the plain format ...
If this is so, why greeting differs in following two commands ? (TeXk instead of TeX; and \write18 added)
$ tex This is TeX, Version 3.14159265 (preloaded format=tex) **
$ initex '\input plain \dump' $ tex -fmt plain This is TeXk, Version 3.14159265 (preloaded format=plain) restricted \write18 enabled. **
Also, I need to override default tex.fmt with local tex.fmt, created from plain.tex:
I put new tex.fmt to /usr/local/share/texmf/web2c/, then run texhash on it.
kpsewhich tex.fmt gives
/usr/local/share/texmf/web2c/tex.fmt, as expected.
But when I run 'tex', it uses default tex.fmt
How to override it?
EDIT: put new tex.fmt to /usr/local/share/texmf/web2c/tex/, and it will work.