what mode_t numbers mean?

[wise]

I am not sure if this is a hardware-related question. In Linux, what do those "mode_t" values mean? Where to find the meaning of mostly used mode_t values? Typically, what does "0666" mean?
/* I use this in creating an entry in /proc" */

Thanks a lot

[bwkaz]

No, this isn't a hardware question. It's a hybrid programming and software one, so I'll send this off to Programming.

But as for the answer, read man 2 chmod -- it lists a bunch of macros you can use with mode_t, the macros' values, and what they mean.

0666, for example, is the bitwise OR of S_IR{USR,GRP,OTH} and S_IW{USR,GRP,OTH}, so with a mode_t of 0666, everyone (the file's owner, the file's group, and others) can read and write to the file. But check the man page for more.