依赖于使用不同的调用名字, 来表现出不同的行为

一些脚本可能会依赖于使用不同的调用名字, 来表现出不同的行为. 如果想要达到这种目的, 一般都需要在脚本中检查$0.

因为脚本只能够有一个真正的文件名, 如果要产生多个名字, 必须使用符号链接. 

#!/bin/bash
# hello.sh: Saying "hello" or "goodbye"
#+          depending on how script is invoked.

# Make a link in current working directory ($PWD) to this script:
#    ln -s hello.sh goodbye
# Now, try invoking this script both ways:
# ./hello.sh
# ./goodbye


HELLO_CALL=65
GOODBYE_CALL=66

if [ $0 = "./goodbye" ]
then
  echo "Good-bye!"
  # Some other goodbye-type commands, as appropriate.
  exit $GOODBYE_CALL
fi

echo "Hello!"
# Some other hello-type commands, as appropriate.
exit $HELLO_CALL