控制流结构

1.退出状态

 exit n

 0 ----退出成功

 1 ----退出失败

 

2.控制结构

if 条件1
then 命令1
elif 条件2
then 命令2
else 命令3

fi

 

#!/bin/sh
#iftest.txt
if [ 10 -lt 12 ]
then
  echo "Yes,10 is less than 12"
else
  echo "No,10 is more than 12"
fi

 

#!/bin/sh
#iftest2.txt
echo -n "Enter your name :"
read NAME
if [ ${NAME} ="" ]
then
  echo "You did not enter any information"
fi

 

[root@localhost yjg]# ./iftest2.txt
Enter your name :
You did not enter any information

 

 3.grep输出检查

 #!/bin/sh
#grepif.txt
if grep 'yjg/>' yjg.txt > /dev/null 2>&1
then
  echo "Great yjg is in the file"
else
  echo "No yjg is not in the file"
fi

 

4.用变量测试输出

#!/bin/sh
#grepstr.txt
echo -n "Enter a list of names:"
read LIST
if echo ${LIST} | grep "Peter" > /dev/null 2>&1
then
   echo "Peter is here"
else
  echo "Peter's not in the list. No comment!"
fi

 

5.文件拷贝测试

#!/bin/sh
#ifcp.txt
if cp yjg2.txt yjg_bak.txt >/dev/null 2>
then
  echo "good copy"
else
  echo "`basename $0`:error could not copy the files" >&2
fi

 

6.当前目录测试

#!/bin/sh
#ifpwd.txt
DIRECTORY=`pwd`
echo $DIRECTORY
if [ "$DIRECTORY" != "/" ]
then
  echo "Your run in the root diretory" >&1
  exit 1
else
  echo "root directory"
  exit 0
fi

 

7.测试传递到脚本的参数个数

 

#!/bin/sh
#ifparam
if [ $# -lt 3 ]
then
  echo "Usage: ` basename $0 ` arg1 arg2 arg3" >&2
  exit 1
fi

echo "arg1: $1"
echo "arg2: $2"
echo "arg3: $3" 

 

8.测试脚本是否为交互模式

#!/bin/sh
#ifinterative.txt
if [ -t ]
then
  echo "We are interactive with a terminal"
else
  echo "We must be running from some background process probably cron or at"
fi
~

 

9.变量设置测试

#!/bin/sh
if [ -z $EDITOR ]
then
  echo "Your EDITOR environment is not set"
else
 echo "Using $EDITOR as the default editor"
fi

 

10.检测执行脚本用户

#!/bin/sh
#ifroot.txt
if [ "$LOGNAME" != "root" ]
then
  echo "You need to be root run this script" >&2
  exit 1
else
 echo "Yes indeed you are $LOGNAME proceed"
fi

 

11.将脚本参数传入系统命令

#!/bin/sh
#ifdirec.txt
DIRCTORY=$1
if [ "`ls -A $DIRCTORY`" = "" ]
then
 echo "$DIRCTORY is indeed empty"
else
 echo "$DIRCTORY is not empty"
fi

 

12.null的用法

#!/bin/sh
#ifmkdir.txt
DIRECTORY=$1
if [ "$DIRECTORY" = 1 ]
then
 echo "Usage:`basename $0` directory to create " >&2
 exit 1
fi

if [ -d $DIRECTORY ]
then
 : #do nothing
else
 echo "The directory does exist"
 echo -n "Create it now? [Y..N] : "
 read ANS
 if [ "$ANS" = "Y" ] || [ "$ANS" = "y" ]
 then
   echo "creating now"
   mkdir $DIRECTORY > /dev/null 2>&1
   if [ $? != 0 ]
   then
     echo "Errors creating the directory $DIRECTORY" >&2
     exit 1
   fi
  else  : #do nothing
  fi
fi

 

#!/bin/sh
#ifcp1.txt
if cp $1 $2 > /dev/null 2>&1
then
 :
else
 echo "`basename $0` : ERROR failed to cp $1 to $2 "
 exit 1
fi

 

 

13.增加和检查整数值

 [root@localhost yjg]# cat count.txt
#!/bin/sh
#count.txt
COUNTER=100
echo "Do you wish to change the counter value currently set a $COUNTER ? [y .. n] "
read ANS
if [ $ANS = "y" ] || [ $ANS ="Y" ]; then
  echo "Enter your to change the value"
  read VALUE
  expr $VALUE + 10 > /dev/null 2>&1
  STATUS=$?

  if [ "$STATUS" = "" ] || [ "$STATUS" != "0" ]; then
    echo " You either entered nothing or non-numeric " >&2
    echo " Sorry now exiting ... counter stays at $COUNTER" >&2
    exit 1
  fi
  COUNTER=`expr $COUNTER + $VALUE`
  echo " Counter now set to $COUNTER "
else
 echo "Counter stays at $COUNTER"
fi

 

14.简单的安全登录脚本

 #!/bin/sh
#ifpass.txt
INVALID_USER=yes
INVALID_PASSWD=yes
SAVEDSTTY=`stty -g`
echo "You are logging into a senstive area"
echo -n "Enter your ID name :"
read NAME
stty -echo
echo "Enter your password :"
read PASSWORD
stty $SAVEDSTTY
if [ "$NAME" = "dave" ]; then
  INVALID_USER=no
fi

if [ "$PASSWORD" = "myday" ]; then
  INVALID_PASSWD=no
fi

if [ "$INVALID_USER" = "yes" -o "$INVALID_PASSWD" = "yes" ]; then
  echo " `basename $0 :` Sorry wrong password or userid"
  exit 1
fi
echo "Correct user id and password given"

 

 

 15.if then...elif then ...else fi

 #!/bin/sh
#ifcataudit.txt
LOCAT_1=/usr/local/yjg/12.log
LOCAT_2=/usr/local/yjg/11.log

if [ -r $LOCAT_1 ]; then
  echo "Using LOCAT_1"
  cat $LOCAT_1
elif [ -r $LOCAT_2 ]; then
  echo "Using LOCAT_2"
  cat $LOCAT_2
else
  " `basename $0` : Sorry the audit file is not readable or cannot be located." >&2
  exit 1
fi

 

16.case 选择

 #!/bin/sh
#caseselect.txt
echo -n "enter a number from 1 to 5 :"
read ANS
case $ANS in
1) echo "you select 1"
 ;;
2) echo "you select 2"
 ;;
3)echo "you select 3"
 ;;
4)echo "you select 4"
 ;;
5)echo "you select 5"
 ;;
*) echo " `basename $0` : This is not between 1 and 5 " >&2
  exit 1
  ;;
esac

 

 

#!/bin/sh
#caseterm.txt
echo " choices are .. vt100,vt102,vt220"
echo -n "enter your terminal type:"
read TERMINAL
case $TERMINAL in
  vt100|vt102 ) TERM=100
  echo "term 100 102"
  ;;
  vt220 ) TERM=220
  echo "term 220"
  ;;
  * )
  echo " `basename $0` : Unknown response " >&2
  echo "setting it to vt100,so there"
  TERM=vt100
  ;;
esac
  export TERM
echo "Your terminal is set to $TERM"

 

17.case 与命令参数传递

 #!/bin/sh
#caseparam.txt
if [ $# != 1 ]; then
  echo "Usage: `basename $0` [start|stop|help] " >&2
  exit 1
fi
 
OPT=$1
 case $OPT in
 start)    
  echo "starting.. `basename $0`"
  ;;
 stop)
  echo "stopping.. `basename $0`"
  ;;
 help)
  ;;   
 *)
  echo "Usage: `basename $0` [start|stop|help]"
  ;;
esac

 

 18.

#!/bin/sh
#caserep.txt
echo "    Weekly Report"
echo -n "What day do you want to run report [Saturday] :"
read WHEN
echo "validating..${WHEN:="Saturday"}"
echo "${WHEN}"
case $WHEN in
Monday)
 ;;
Sunday)
 ;;
*)
 echo " Are you nuts!,this report can only be run on" >&2
 echo " on a Saturday,Sunday or Monday" >&2
 exit 1
 ;;
esac

 

19.for 循环

 对for循环使用ls命令

 #!/bin/sh
#forls.txt
for loop in ` ls `
do
  echo $loop
done

20.对for循环使用参数

 连接服务器

 #!/bin/sh
#forping.txt
HOSTS="itserv dnssevr acctsmain ladpd ladware"
for loop in $HOSTS
do
  ping -c 2 $loop
done

 

备份多个文件

#!/bin/sh
#forUC.txt
for files in ` ls *.log `
do
  cp $files '/usr/local/yjg/nec' > /dev/null 2>&1
done

 

大小写转化

#!/bin/sh
#forUC.txt
for files in ` ls *.log `
do
 cat $files | tr "[ a-z ]" "[ A-Z ]" > $files.UC
done

 

#!/bin/sh
#forsed.txt
for files in `ls *.log`
do
 sed -e "/^$/d" $files >$files.HOLD
 mv $files.HOLD $files
done

 

break ,continue

#!/bin/sh
#breakout.txt
while :
do
  echo -n "Enter any number [ 1..5 ] :"
  read ANS
  case $ANS in
    1|2|3|4|5)
    echo "great you entered a number between 1 and 5"
    ;;
  *)
    echo "Wrong number .. bye"
    break
  esac
done

 

#!/bin/sh
#whilecontinue.txt
SAVEDIFS=$IFS
IFS=:
INPUT_FILE=name2.txt
NAME_HOLD="Peter James"
LINE_NO=0

if [ -s $INPUT_FILE ]; then
  while read NAME DEPT ID
  do
    LINE_NO=` expr $LINE_NO + 1 `
    if [ $LINE_NO -le 2 ]; then
      continue

    fi
    if [ "$NAME_HOLD" = "$NAME" ]; then
       continue;
    else
       echo " Now processing ... $NAME  $DEPT  $ID "
    fi
  done < $INPUT_FILE

IFS=$SAVEDIFS

else
  echo " `basename $0 ` : Sorry file not found or there is no data in the file " >&2
  exit 1
fi

 

菜单

 #!/bin/sh
#menu.txt
MYDAY=`date +%d/%m/%Y`
THIS_HOST=`hostname -s`
USER=`whoami`
while :
do
  tput clear
  cat << MAYDAY
  -----------------------------------------------------------
 
  User: $USER          Host:$THIS_HOST        Date:$MYDATE
 
  ------------------------------------------------------------
                1: List files in current directory
                2: Use  the vi editor
                3: See who is one the system
                H: Help screen
                Q: Exit menu
  -----------------------------------------------------------
MAYDAY #---------------前不能有空格

echo -e -n "/tYou Choice [1,2,3,H,Q] >"
read CHOICE
case $CHOICE in
1) ls
   ;;
2) vi
   ;;
3) who
   ;;
H|h)
   cat << MAYDAY
     This is the help screen,nothing here yet to help you!
MAYDAY #---------------前不能有空格
  ;;
Q|q)
  exit 0
  ;;
*)
  echo -e "/t/007unknown user response"
  ;;
esac
echo -e -n "/tHit the return key to continue"
read DUMMY
done