Shell Notepad

来源：互联网发布：信用卡淘宝如何套现编辑：程序博客网时间：2024/05/18 01:19

1 单引号和双引号的区别
单引号严格一些。它可以防止任何变量扩展。双引号可以防止通配符扩展但允许变量扩展。

2 Use case to select OS type
# Moved shell code from '.machtype' into here so that one less process
# is executed.
PLATFORM="unknown"
if [ -f /usr/5bin/uname ] ; then
    OS_TYPE=`/usr/5bin/uname -r`
    PLATFORM=`/usr/5bin/uname -m`
else
    if [ -f /usr/bin/uname ] ; then
      OS_TYPE=`/usr/bin/uname -r`
      PLATFORM=`/usr/bin/uname -m`
    else
      if [ -f /bin/uname ] ; then
OS_TYPE=`/bin/uname -r`
PLATFORM=`/bin/uname -m`
    fi
fi

# Note that SunOS 5.0 can run SunOS 4.x binaries, but not vice-versa.
# Note that SysV88 R4x can run SysV88 R32 binaries, but not vice-versa.

case $PLATFORM in

    #############################################
    # We are a Sun-4 running ...
    #############################################
    sun4*)
    case $OS_TYPE in
      4*)
   PLATFORM=sun4 ;; # ... SunOS 4.x. We can't run ELF binaries.

      5*)
   PLATFORM=sun44 ;; # ... SunOS 5.x. We run both SunOS 4.x
                             # binaries and SunOS 5.x ELF binaries.
    esac ;;

    #############################################
    # We're a Sun-3.
    #############################################
    sun|sun3*)
        PLATFORM=sun3 ;;

    #############################################
    # We're running Solaris on x86
    #############################################
    i86pc)
    PLATFORM=pc ;;

    #############################################
    # We're a 68K Moto VME.
    #############################################
    M68030)
     PLATFORM=m68k ;;

    #############################################
    # We're an 88K MCG VME running R32.
    # We can not run R4x ELF binaries.
    #############################################
    M88100)
     PLATFORM=m88k ;;

    #############################################
    # We're an 88K MCG VME running R4x.
    # We run both R32 COFF binaries as well as R4x ELF binaries.
    #############################################
    m88k)
   PLATFORM=m88k4 ;;

    #############################################
    # We're an HP 9000 workstation.
    #############################################
    9000/7*)
      PLATFORM=hp97 ;;

9000/*)
PLATFORM=hp9 ;;

esac
# End of .machtype code

3 联合逻辑运算
if [ "x$PLATFORM" != "x" -a ! -h /tmp/gsmtt/bin ]; then

! Unary negation operator. -a Binary and operator.

4 重定向（屏蔽）输入输出
rm -rf /tmp/tt >/dev/null 2>&1

5 exec
调用exec后面的命令将不会被执行（进程覆盖）

6 关于赋值时的空格--不要空格！
对：
a='$0'
错：
a = '$0'
a= '$0'
a = '$0'

Reference:
shell编程（1）
shell编程（2）
shell编程（3）
shell编程学习笔记(1)
shell编程学习笔记(2)
Bourne Shell及shell编程(1)