docs/marvell/howto/save_build_log.txt - T108 - Gitiles

 Logging Everything of make process

 The console's scrollback buffer will often prove to be too small to keep the full output of the package build process.

 There are moments you want to enable logging of the build process so that you can comfortably search(grep) through the logfiles
 when there appears to be a problem with building process

 The command looks like this:

  make -j2 V=99  2>&1 | tee build.log

 0 is stdin. 1 is stdout. 2 is stderr

 There's one way to remember this construct (maybe it is not entirely accurate):
  -------------
  First of all, 2>1 looks like a very good way to redirect stderr to stdout. but remember,
 it has a very harmful disadvantage: it may actually be interpreted as "redirect stderr to a file named 1".
  -------------
  & indicates that what follows is a file descriptor and not a filename. So the construct becomes: 2>&1.
  -------------
  >& is shell syntax for "fold a file descriptor into another", you can also interprete it as
 "it is the syntax to redirect a stream to another file descriptor"

 The part " | tee build.log" causes a file build.log to be created (if it does not yet exist) and a copy of the text that
 your script displays on the console is going to be written to it.
 Any previous content of that logfile will be overwritten.

 The part "2>&1" means that you will also catch the ERROR output of failed commands. You would normally not notice,
 but programs can write their output to "standard output" as well as "error output".
 These are two separate "channels" if you like, and since the tee command will only catch "standard output" and
 duplicate it into the target file, you will have to explicitly add "error output" as well.
 Remember, the error output will often be the stuff you're most interested in!


 By using this command, you are still able to watch the proceedings of the package build process on your console,
 and afterwards you can open the log file in an editor at your leisure.

 look for the info:

 	•Compilation errors ( grep -iE "(error|failed)" )
 	•Header/include/library files missing ( grep -iE "(not found|unavailable)" )

 ref: http://tldp.org/LDP/abs/html/io-redirection.html
	Logging Everything of make process

	The console's scrollback buffer will often prove to be too small to keep the full output of the package build process.

	There are moments you want to enable logging of the build process so that you can comfortably search(grep) through the logfiles
	when there appears to be a problem with building process

	The command looks like this:

	make -j2 V=99 2>&1 \| tee build.log

	0 is stdin. 1 is stdout. 2 is stderr

	There's one way to remember this construct (maybe it is not entirely accurate):
	-------------
	First of all, 2>1 looks like a very good way to redirect stderr to stdout. but remember,
	it has a very harmful disadvantage: it may actually be interpreted as "redirect stderr to a file named 1".
	-------------
	& indicates that what follows is a file descriptor and not a filename. So the construct becomes: 2>&1.
	-------------
	>& is shell syntax for "fold a file descriptor into another", you can also interprete it as
	"it is the syntax to redirect a stream to another file descriptor"

	The part " \| tee build.log" causes a file build.log to be created (if it does not yet exist) and a copy of the text that
	your script displays on the console is going to be written to it.
	Any previous content of that logfile will be overwritten.

	The part "2>&1" means that you will also catch the ERROR output of failed commands. You would normally not notice,
	but programs can write their output to "standard output" as well as "error output".
	These are two separate "channels" if you like, and since the tee command will only catch "standard output" and
	duplicate it into the target file, you will have to explicitly add "error output" as well.
	Remember, the error output will often be the stuff you're most interested in!


	By using this command, you are still able to watch the proceedings of the package build process on your console,
	and afterwards you can open the log file in an editor at your leisure.

	look for the info:

	•Compilation errors ( grep -iE "(error\|failed)" )
	•Header/include/library files missing ( grep -iE "(not found\|unavailable)" )

	ref: http://tldp.org/LDP/abs/html/io-redirection.html