[arch-projects] [mkinitcpio][PATCH 09/26] functions: specify the delimiter to xargs

[Dan McGee]

On Mon, Sep 26, 2011 at 10:48 PM, Dave Reisner <d at falconindy.com> wrote:
> On Mon, Sep 26, 2011 at 10:46:57PM -0500, Dan McGee wrote:
>> On Mon, Sep 26, 2011 at 8:22 PM, Dave Reisner <d at falconindy.com> wrote:
>> > Without specifying this, xargs will split arguments on whitespace as
>> > well as newlines, and will interpret quoting and backslashes. When the
>> > delimiter is specified, every character is taken literally and only the
>> > given delimiter in honored.
>> >
>> > This sidesteps issues with broken modalias files as evidenced by a
>> > MacBookAir3,1 or the bbs thread below:
>> >
>> > https://bbs.archlinux.org/viewtopic.php?pid=971853
>> >
>> > Also fixes FS#25450.
>> >
>> > Signed-off-by: Dave Reisner <dreisner at archlinux.org>
>> > ---
>> >  functions |    2 +-
>> >  1 files changed, 1 insertions(+), 1 deletions(-)
>> >
>> > diff --git a/functions b/functions
>> > index 8ce24ea..7f9202f 100644
>> > --- a/functions
>> > +++ b/functions
>> > @@ -117,7 +117,7 @@ auto_modules() {
>> >
>> >     IFS=$'\n' read -rd '' -a mods < \
>> >         <(find /sys/devices -name modalias -exec sort -u {} + |
>> > -        xargs modprobe -d "$BASEDIR" -aRS "$KERNELVERSION" |
>> > +        xargs -d $'\n' modprobe -d "$BASEDIR" -aRS "$KERNELVERSION" |
>> Dollar sign what? /me doesn't follow this at all, a comment would be great.
>
> consult your manual, sir!
>
>  Words  of the form $'string' are treated specially. The word expands
>  to string, with backslash-escaped characters replaced as specified by
>  the ANSI C standard.  Backslash escape sequences, if present, are
>  decoded.
>
> In other words, its expanded in place. Yeah, this seems elementary to
> me, but I suppose its comment worthy.

Well when you say "consult your man page", I thought to myself, "Damn,
did I really miss that? Let's read again."

       --delimiter=delim
       -d delim
              Input  items  are terminated by the specified character.  Quotes
              and backslash are not special; every character in the  input  is
              taken  literally.   Disables  the  end-of-file  string, which is
              treated like any other argument.  This can be used when the  in‐
              put  consists  of simply newline-separated items, although it is
              almost always better to design your program to use --null  where
              this is possible.  The specified delimiter may be a single char‐
              acter, a C-style character escape such as \n,  or  an  octal  or
              hexadecimal escape code.  Octal and hexadecimal escape codes are
              understood as for the printf command.   Multibyte characters are
              not supported.

Nope! Nothing there.

Then I realized "Oh! He is talking about some bash feature and THAT is
the manpage I'm supposed to be reading."

It isn't elementary to those of us that don't use shell as much as
you, and RTFM on a 5439 line gargantuan manpage is not my idea of fun,
not to mention the 118 lines of hits for the literal '$' character
(because I would have no idea in hell how else to find it).

-Dan