file-comparison.sh

来自「BASH Shell 编程 经典教程 《高级SHELL脚本编程》中文版」· Shell 代码 · 共 33 行

#!/bin/bash

ARGS=2  # 脚本需要两个参数. 
E_BADARGS=65
E_UNREADABLE=66

if [ $# -ne "$ARGS" ]
then
  echo "Usage: `basename $0` file1 file2"
  exit $E_BADARGS
fi

if [[ ! -r "$1" || ! -r "$2" ]]
then
  echo "Both files to be compared must exist and be readable."
  exit $E_UNREADABLE
fi

cmp $1 $2 &> /dev/null  # /dev/null将会禁止"cmp"命令的输出.
#   cmp -s $1 $2 与上边这句的结果相同("-s"选项是禁止输出(silent)标志)
#   感谢Anders Gustavsson指出这点.
#
# 使用'diff'命令也可以, 比如,   diff $1 $2 &> /dev/null

if [ $? -eq 0 ]         # 测试"cmp"命令的退出状态.
then
  echo "File \"$1\" is identical to file \"$2\"."
else  
  echo "File \"$1\" differs from file \"$2\"."
fi

exit 0