[gentoo-user] linux make modules solved

[gentoo-user] linux make modules solved

[Justin R Findlay]

I finally figured out why linux wouldn't build its modules.  Although I
learned a lot about make it was because I had set

GREP_OPTIONS="--color=always"

in my /root/.bashrc which is sourced by shell invocations from make (and
odd shell scripts as well, like configure scripts).  So, the lesson is,
don't modify common shell utilities in ~/.bashrc or strange things might
happen.  There are a couple of safe alternatives for grep colors.  You
can move GREP_OPTIONS to ~/.bash_profile which is only sourced by login
shells, or you can define

alias cgrep="--color=always"

In keeping with the shell color theme I have also defined:

alias less="less -R"
alias tree="tree -C"


Justin
-- 
gentoo-user@gentoo.org mailing list

Re: [gentoo-user] linux make modules solved

[Daniel Drake]

Justin R Findlay wrote:
> I finally figured out why linux wouldn't build its modules.  Although I
> learned a lot about make it was because I had set
> 
> GREP_OPTIONS="--color=always"

Using "--color=auto" would have circumvented this problem and still 
given you pretty colours when you run grep from the console.

Daniel

-- 
gentoo-user@gentoo.org mailing list

Re: [gentoo-user] linux make modules solved

[Mick]

On 16/06/06, Daniel Drake <dsd@gentoo.org> wrote:
> Justin R Findlay wrote:
> > I finally figured out why linux wouldn't build its modules.  Although I
> > learned a lot about make it was because I had set
> >
> > GREP_OPTIONS="--color=always"
>
> Using "--color=auto" would have circumvented this problem and still
> given you pretty colours when you run grep from the console.

I am getting confused here:  why is module building related to setting
grep's colour option?
-- 
Regards,
Mick
-- 
gentoo-user@gentoo.org mailing list

Re: [gentoo-user] linux make modules solved

[Bo Ørsted Andresen]

[-- Attachment #1: Type: text/plain, Size: 543 bytes --]

On Saturday 17 June 2006 13:48, Etaoin Shrdlu wrote:
> Using --color=auto, on the
> other hand, is the correct way to do the "right" thing, ie grep
> itself "knows" whether it should emit escape sequences to colorize the
> output (if it's really outputting to terminal) or not (if, for example,
> it's called from inside a command substitution).

Just to show you the purpose of adding --color=always. Try the following:

# echo hello | grep --color=auto ll | less

# echo hello | grep --color=always ll | less

-- 
Bo Andresen

[-- Attachment #2: Type: application/pgp-signature, Size: 189 bytes --]

Re: [gentoo-user] linux make modules solved

[Mick]

On 17/06/06, Etaoin Shrdlu <shrdlu@unlimitedmail.org> wrote:
> On Saturday 17 June 2006 12:15, Mick wrote:
>
> > I am getting confused here:  why is module building related to setting
> > grep's colour option?
>
> There is probably some script that parses the output of grep, and,
> with --color=always, this includes terminal control characters and
> escape sequences which confuse the parser. Using --color=auto, on the
> other hand, is the correct way to do the "right" thing, ie grep
> itself "knows" whether it should emit escape sequences to colorize the
> output (if it's really outputting to terminal) or not (if, for example,
> it's called from inside a command substitution).
>
> The following works:
> echo "hello" | grep ello | grep hello
>
>
> The following does not work, since the output of the first grep
> contains "garbage" (from the point of view of the second grep) between
> the "h" and the "e":
>
> echo "hello" | grep --color=always ello | grep hello   # does not work
>
>
> Finally, the next one works, because the first grep knows that colorizing
> the output here is useless and does not emit escape sequences:
>
> echo "hello" | grep --color=auto ello | grep hello     # works

Thanks!  Nice explanation.
-- 
Regards,
Mick
-- 
gentoo-user@gentoo.org mailing list

Re: [gentoo-user] linux make modules solved

[Etaoin Shrdlu]

On Saturday 17 June 2006 12:15, Mick wrote:

> I am getting confused here:  why is module building related to setting
> grep's colour option?

There is probably some script that parses the output of grep, and, 
with --color=always, this includes terminal control characters and 
escape sequences which confuse the parser. Using --color=auto, on the 
other hand, is the correct way to do the "right" thing, ie grep 
itself "knows" whether it should emit escape sequences to colorize the 
output (if it's really outputting to terminal) or not (if, for example, 
it's called from inside a command substitution).

The following works:
echo "hello" | grep ello | grep hello


The following does not work, since the output of the first grep 
contains "garbage" (from the point of view of the second grep) between 
the "h" and the "e":

echo "hello" | grep --color=always ello | grep hello   # does not work


Finally, the next one works, because the first grep knows that colorizing 
the output here is useless and does not emit escape sequences:

echo "hello" | grep --color=auto ello | grep hello     # works

HTH
-- 
gentoo-user@gentoo.org mailing list