czwartek, 12 stycznia 2012

Linux From Scratch

Nice page with lots of informations how to create Linux system. This can be really useful for embedded systems developers.

Some information are quite universal e.g. how to build gcc. There is explicit invocation of 'configure' for gcc with proper settings for include and lib directories for 'mpfr'.

Here tag

"Here Tag" - how to enter multi-line entry to commands.

cat >file <<HERE
> ab asd ew
> as ggs sfdw er we

Entry "<<HERE" tells what word is finishing entry. The word is arbitrary (e.g. EOF, STOP, blahblah, ...). The tag is not written to file.
What is important to notice is "<<" and not "<".
Multi-line input finishes when tag is entered, but tag must be only input in line (i.e. without spaces, other characters). Tag can be entered as part of text in line and in that case not considered "here tag".
Here tags are available in bash, perl, awk and others.


Interesting description of UBIFS (UBI File-System) and what might be more important description of main features of JFFS2 can be found here.