[CLUE-Cert] scripting fun

[Lynn Danielson]

I think the following should work:

egrep "^s[0-9]+:" /etc/passwd | cut -f1 -d: | xargs -r usermod -G us,exclusiv

egrep wil print all lines from the passwd file which begin with "s" followed
by any number of numerals followed by a colon.  Cut will filter for the first
field which is delimited with a colon.  Xargs will pass its input to usermod
as arguments.

Lynn


jdlabarnhart at home.com wrote:
> 
> Hello all,
> 
> When I setup a sysad class I make groups us, them, exclusiv and secret.
> I need to add students to the us and exclusiv groups. I do this by using
> a "for" loop.
> 
> for User in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
> do
> usermod -G us,exclusiv s$User
> done
> 
> A simple 4 line script. Now what I would like to do is get rid of the 1
> 2 3 ... line of the for loop and do something like
> 
> cat /etc/password | xargs grep s*
> for User in $SUser
> do
> usermod -G us,exclusiv s$User
> done
> 
> I know what the users are but would like to automate the process a
> little more. There are goals that need to be met.
> 
> 1. Small script. 5 -10 lines at max. make it easy to remember.
> 2. Done in memory. While we could do this with temp files we want to do
> this without. makes it more fun.
> 
> Why would we do something like this? How about that a development group
> is put together to do some work. They will work on project X and will
> need to access the same documents.
> 
> /etc/passwd
> root:x:0:0:root:/root:/bin/bash
> bin:x:1:1:bin:/bin:
> daemon:x:2:2:daemon:/sbin:
> adm:x:3:4:adm:/var/adm:
> sync:x:5:0:sync:/sbin:/bin/sync
> shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
> halt:x:7:0:halt:/sbin:/sbin/halt
> operator:x:11:0:operator:/root:
> ftp:x:14:50:FTP User:/var/ftp:
> sympa:x:89:89:Sympa Mailing list manager:/var/lib/sympa:/bin/bash
> nobody:x:99:99:Nobody:/:
> alias:x:400:401:qmail alias user:/var/qmail/alias:/bin/true
> s1:x:501:501::/home/s1:/bin/bash
> s2:x:502:502::/home/s2:/bin/bash
> s3:x:503:503::/home/s3:/bin/bash
> s4:x:504:504::/home/s4:/bin/bash
> s5:x:505:505::/home/s5:/bin/bash
> 
> /etc/group
> root:x:0:root
> bin:x:1:root,bin,daemon
> daemon:x:2:root,bin,daemon
> sys:x:3:root,bin,adm
> adm:x:4:root,adm,daemon
> tty:x:5:
> disk:x:6:root
> lp:x:7:daemon,lp
> mem:x:8:
> kmem:x:9:
> wheel:x:10:root
> us:x:401:
> them:x:402:
> excluciv:403:
> secret:404:
> s1:x:501:
> s2:x:502:
> s3:x:503:
> s4:x:504:
> s5:x:505: