# ls -l * |grep "^-"|wc -l ---- to count files
  
  # ls -l * |grep "^d"|wc -l ----- to count dir

  ls -F | grep /$ 或者 alias sub = "ls -F | grep /$"（linux）
  
  ls -l | grep "^d" 或者 ls -lL | grep "^d" （Solaris）

head -5 /etc/passwd

tail -10 /etc/passwd

sed -n '5,10p' /etc/passwd 

$find . -type f -exec grep "the string you want find…" {} ; -print

  .
  
  `--shellp
  
  `--updates
  
  `--wu-ftpd-2.4
  
  | `--doc
  
  | | `--examples
  
  | `--src
  
  | | `--config
  
  | | `--makefiles
  
  | `--support
  
  | | `--makefiles
  
  | | `--man
  
  | `--util

 #!/bin/sh
  
  # dtree: Usage: dtree [any directory]
  
  dir=${1:-.}
  
  （cd $dir; pwd）
  
  find $dir -type d -print | sort -f | sed -e "s,^$1,," -e "/^$/d" -e "s,[^/]*/（[^/]*）$,`----1," -e "s,[^/]*/,| ,g"

cut -d: -f 1 /etc/passwd >; /tmp/users

  cut -c3-5 /etc/passwd

 #!/bin/bash
  
  # Encrypt file with vim
  
  if （test $# -lt 2） then
  
  echo Usage: decrypt password filename
  
  else
  
  vim -e -s -c ":set key=$1" -c ':wq' $2
  
  echo "$2 encrypted."
  
  fi
  
  [weeder@SMTH weeder]$ for file in *.txt ; do encrypt test $file ; done
  
  test2.txt encrypted.
  
  test4.txt encrypted.
  
  test9.txt encrypted.
  
  kick.txt encrypted.
  
  echo "$2 encrypted."
  
  fi
  
  [weeder@SMTH weeder]$ for file in *.txt ; do encrypt test $file ; done
  
  test2.txt encrypted.
  
  test4.txt encrypted.
  
  test9.txt encrypted.
  
  kick.txt encrypted.
  
  too_old.txt encrypted.
  
  too_old_again.txt encrypted.
  
  bg5.txt encrypted.
  
  [weeder@SMTH weeder]$

  alluser: :include:/etc/mail/allusers

awk -F: '$3 >; 100 { print $1 }' /etc/passwd >; /etc/mail/allusers

  ldd /bin/ls

echo "系统当前用户"
  
  echo "---------------"
  
  who | awk '{print $2}'
  
  echo "---------------"
  
  echo "输入要杀死终端的终端号："
  
  read $TTY
  
  kill -9 ${K}=`ps -t $TTY | grep [0-9] | awk '{print $1}'`