BASH + Best method of converting fields to variables

Ow Mun Heng Ow.Mun.Heng at wdc.com
Sat Jul 17 20:03:44 UTC 2004


On Sat, 2004-07-17 at 05:43, Karsten Hopp wrote:
> On Fri, Jul 16, 2004 at 10:29:38PM -0400, Aaron Gaudio wrote:
> > Behold, Ow Mun Heng <Ow.Mun.Heng at wdc.com> hath decreed:
> > > Guys,
> > > 
> > > 	Writing a batch_create_new_user script.
> > > input is a file with this format
> > > 
> > > Username:Full Name:Default Group:Default Shell:Home Directory:Password
> > >  
> > > and the using those fields ($1 $2 $3 etc) and passing then to the useradd program
> > > 
> > > I'm having some trouble getting bash to get the positional fields into variables which I
> > > can then plug into useradd
> > > 
> > > eg:
> > > pseudo code
> > > for each line in input file
> > >   do
> > > 	username=$1
> > > 	name=$2
> > > 	useradd -c "$2" $1
> > >   done
> > > 
> > > I ended up using awk, which works but seems complicated
> > > 
> > > 	eval `awk -F ':' \
> > >         '{printf ("useradd -c \"%s\" ",$2)}; \
> > >         length($3)>0 {printf ("-g %s ",$3)}; \
> > >         length($4)>0 {printf ("-s %s ",$4)}; \
> > >         length($5)>0 {printf ("-d %s ",$5)}; \
> > >         {printf ("%s\n;",$1)};' $1`
> > > 
> > > Can it be done using bash itself? (without calling awk)
> > > Actually I was hoping I can get awk to get the fields for the variables
> > 
> 
> How about using the IFS variable for this ?
> set IFS to ':' and run a for...done loop over each line of the input file.

I'm not sure how that can be used. 

One other thing which I found is that by using awk, I'm actually
processing the file all at once. (as the awk code above shows). I'm not
sure how I can get BASH to actually process it line-per-line like tcsh's
foreach.

Maybe I can learn up on using awk's $NR variable, to get it to
auto-increment so that I read it line-by-line and process it that way.

Right now, my random password generator function is making the _same_
default password for _all_ users. That's Not too great.

Dang.. the more I write, the more complicated I'm making it.

Thanks for the help



> 
> --
>  Karsten Hopp <karsten at redhat.de>   GPG 1024D/70ABD02C
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-- 
Ow Mun Heng
Fedora GNU/Linux Core 2 on D600 1.4Ghz CPU kernel
2.6.7-2.jul1-interactive 
Neuromancer 12:57:04 up 14:59, 7 users, load average: 0.61, 0.97, 0.83 





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