Re: Our Most Precious Resource: Programmer Time (was Re: long term goals)
Philip Brown <phil@bolthole.com> wrote:
>
> 1. Singleshot external programs, with internal stuff.
> For example, in POSIX shell, instead of using
> val=`expr $var1 + var2`
> you can use the *built-in* math functions, to do
> val=$(($var1 + $var2))
Agreed.
> Similarly, replace
> if [ xxx ]
> with
> if [[ xxx ]]
> The first is EXTERNAL. the second is built-in to POSIX-sh
Nope, the first one is built-in to all the shells that I know of. While
the second one is not defined by POSIX and not supported by ash.
> 2. replace step-by-step I/O with external functions
> Funny how that seems to contradict, eh? :-)
> But if you have a big old loop like
> while true ; do
> read xyz
> set $xyz
> do stuff with vars
> done
> it can often be speeded up drastically by rewriting that loop in AWK.
> That's what awk is for.
Definitely. Especially since read has to read(2) byte-by-byte.
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