ls -l
-rw-rw-rw-   1 user     group          26 Jun 10 13:27 invalid.txt
-rw-rw-rw-   1 user     group        1049 Jun 10 13:44 reciter.pl
-rw-rw-rw-   1 user     group          36 Jun 10 13:28 valid.txt

cat invalid.txt
dfd
wdfq


qwef
z2=0.7

cat valid.txt
adf
df
x2=0.7
z2=0.7
some_t2=0.7