1. who | cut -d‘‘ -f1 | sort -u

2.cut -d: -f7 /etc/passwd | uniq -c | sort -rn | head -n -1 

3.sort -t: -k3 -n /etc/passwd |tail -n -10  | tr‘a-z‘ ‘A-Z‘ > tmp/maxusers.txt

4.ifconfig | head -n -2 | tail -n -1 | cut -d: -f2 | tr -d "Bcast"

5.ls /var/|wc -w 

6.sort -t: -k3n /etc/group | head -n -10 | cut -d: -f1

7.cat /etc/fstab /etc/issue > /tmp/etc.test

8.groupadd -g 2016 disto

  useradd  -u 1005 -g distro mandriva 

  useradd  -u 1100 -d /home/linux mageia

  echo "mageedu" | passwd --stdin mageia

  userdel mandriva

  useradd -u 2002 -g disrto -G peguin slackware

  usermod -s /bin/tcsh slackware 

  usermod -aG admins slackware 

  passwd -n 3 -x 183 -w 3 slackware 

  useradd -u 3003 -g clouds -G peguin,nova openstack 

  useradd -s /sbin/nologin mysal 

  echo "passwd" | passwd stdin "openstack"

9.cp -r /etc/skel /home 

  mv /home/skel /home/tuser1 

  chmod g-r,o-r /home/tuser1

 ll -a /home/tuser1 | grep tuser1 

 chmod g-r,o-r /home/tuwer1/.*

ll -a /home/tuser1 

10.cat /etc/passwd | grep -E ^(s|S)

   cat /etc/passwd | grep -E -i ^s

   cat /etc/passwd | grep -E ^[sS]

   cat /etc/passwd | grep -e "^s" -e "^S"

11.cat /etc/passwd | grep -E -v "/bin/nologin$"

12.  cat /etc/passwd | grep -E "/bin/nologin$"

13. cat /etc/passwd | grep "\<[0-9]\{2,3\}\>"    

14. grep "^#[[:space:]]\+[^[:space:]]" /etc/rc.d/rc.sysinit

15.netstat -tan | grep "LISTEN[[:space:]]*$"

16.useradd bash

useradd testbash

useradd basher

useradd -s /sbin/nologin nologin

# egrep "^([[:alnum:]]+\>).*\1$" /etc/passwd

全新Linux+Python高端运维班第二次作业