将上次修改的二进制文件复制到另一个二进制文件

我想比较两个二进制文件(非常小，每个100Kb)，并将最老的文件替换为最后修改的文件。

我已经创建了一个简单的脚本，但我需要你的帮助，使其正常运行:

#!/bin/sh
# select the two files
FILE1="/dir1/file1.binary"
FILE2="/dir2/file2.binary"
# create the hash of the two files
HASH1="$(md5sum $FILE1 | cut -c 1-32)"
HASH2="$(md5sum $FILE2 | cut -c 1-32)"
# compare the two hashes
if [ "$HASH1" == "$HASH2" ];
# if the two hashes are the same, exit
then
echo "the two files are identical"
exit 0
# otherwise compare which of them has been last modified
fi
DATE1="(stat -c %Y $FILE1)"
DATE2="(stat -c %Y $FILE2)"
# if FILE1 is newer than FILE2, replace FILE2 with FILE1
if [ "${DATE1}" -gt "${DATE2}" ];
then
cp $FILE1 $FILE2
echo "${FILE2} was replaced by ${FILE1}"
# if FILE2 is newer than FILE1, replace FILE1 with FILE2
fi
cp $FILE2 $FILE1
echo "${FILE1} was replaced by ${FILE2}"
exit 0

该文件似乎工作(至少如果两个文件是相同的)，但如果一个文件被修改，我收到以下错误:

line 24: [: {(stat -c %Y test1)}: integer expression expected

怎么了?

顺便问一下，有没有更好的方法来解决这个问题?

感谢

非常感谢大家的帮助。下面是脚本现在的样子。QNAP在QTS上也有通知，但如果在其他地方运行或不需要，它可以被删除。

#!/bin/sh
# select the two files
FILE1="/dir1/file1"
FILE2="/dir2/file2"
# use or create a log file with timestamp of the output
LOG="/dir1/ScriptLog.txt"
TIMESTAMP=$(date +"%Y-%m-%d %Hh:%M")
if [ ! -e $LOG ]; then
    touch $LOG
    echo "$TIMESTAMP - INFO: '$LOG' does not exists but has been created." >&2
# else
#   echo "$TIMESTAMP - INFO: '$LOG' exists and it will be used if any change to '$FILE1' 
#   or to '$FILE2' is needed." >&2
fi
# You can also pass the two file names as arguments for the script
if [[ $# == 2 ]]; then
    FILE1=$1
    FILE2=$2
fi
# check if the two files exist and are regular
if [ -f "$FILE1" -a -f "$FILE2" ]; then
    # meanwhile compare FILE1 against FILE2
    # if files are identical, stop there
    if cmp "$FILE1" "$FILE2" 2>/dev/null>/dev/null; then
        echo "$TIMESTAMP - INFO: '$FILE1' and '$FILE2' are identical." >&2 | >> $LOG
    # if FILE1 is newer than FILE2, copy FILE1 over FILE2
    elif [ "$FILE1" -nt "$FILE2" ]; then
        if cp -p "$FILE1" "$FILE2"; then
        echo "$TIMESTAMP - INFO: '$FILE1' replaced '$FILE2'." >&2 | >> $LOG
            # if copy is successful, notify it into QTS
            /sbin/notice_log_tool -a "$TIMESTAMP - INFO: '$FILE1' replaced '$FILE2'." --severity=5 >&2
        else
            echo "$TIMESTAMP - ERROR: FAILED to replace '$FILE2' with '$FILE1'." >&2 | >> $LOG
            exit 1
        fi
    # if FILE1 is older than FILE2, copy FILE2 over FILE1
    elif [ "$FILE1" -ot "$FILE2" ]; then 
        if cp -p "$FILE2" "$FILE1"; then
            echo "$TIMESTAMP - INFO: '$FILE2' replaced '$FILE1'." >&2 | >> $LOG
            # if copy is successful, notify it into QTS
            /sbin/notice_log_tool -a "$TIMESTAMP - INFO: '$FILE2' replaced '$FILE1'." --severity=5 >&2
        else
            echo "$TIMESTAMP - ERROR: FAILED to replace '$FILE2' with '$FILE1'." >&2 | >> $LOG
            exit 1
        fi
    # if two files are not identical but with same modification date
    else
        echo "$TIMESTAMP - ERROR: We should never reach this point. Something is wrong in the script." >&2 | >> $LOG
        exit 1
    fi
    # if one file does not exist or is not valid, exit
else
    echo "$TIMESTAMP - ERROR: One of the files does not exist, has been moved or renamed." >&2 | >> $LOG
        # if error, notify it into QTS
        /sbin/notice_log_tool -a "$TIMESTAMP - ERROR: One of the files does not exist, has been moved or renamed." --severity=5 >&2
    exit 1
fi

我还建议对其进行重构，既可以简化代码，又可以节省CPU周期。

#!/bin/sh
# If both files exist....    
if [ -f "$1" -a -f "$2" ]; then
  # If they have the same content...
  if cmp "$1" "$2" >/dev/null 2>/dev/null; then
    echo "INFO: These two files are identical." >&2
  # If one is newer than the other...
  elif [ "$1" -nt "$2" ]; then
    if cp -p "$1" "$2"; then
      echo "INFO: Replaced file '$2' with '$1'." >&2
    else
      echo "ERROR: FAILED to replace file." >&2
      exit 1
    fi
  # If the other is newer than the one...
  elif [ "$1" -ot "$2" ]; then
    if cp -p "$2" "$1"; then
      echo "INFO: Replaced file '$1' with '$2'." >&2
    else
      echo "ERROR: FAILED to replace file." >&2
      exit 1
    fi
  else
    echo "ERROR: we should never reach this point. Something is wrong." >&2
    exit 1
  fi
else
  echo "ERROR: One of these files does not exist." >&2
  exit 1
fi

你可能会发现一些有用的东西。

这避免了对每个文件计算md5。虽然比较总和对于像您这样的小文件来说可能没有问题，但随着文件的增长，它会变得非常昂贵。这是完全没有必要的，因为你有cmp命令可用。最好养成编写代码的习惯，当你在下一个项目中循环使用它时，修改更少。
if语句运行一个命令，通常是[或[[，但也可以是任何命令。在这里，我们在if中运行cmp和cp，以便我们可以轻松检查结果。
不再使用stat了。虽然您可能永远不会超越Linux，但牢记可移植性始终是一个好主意，如果您可以使您的脚本可移植，那就太好了。

bash

/bin/sh

缩进有帮助。您可能希望在自己的脚本中采用它，这样您就可以更好地直观地了解哪些命令与正在测试的各种条件相关联。

像下面这样简单一点怎么样?

#!/bin/sh
# select the two files from cli
# $1 = current file
# $2 = new file
FILE1=$1
FILE2=$2
# otherwise compare which of them has been last modified
DATE1=`(stat -c %Y $FILE1)`
DATE2=`(stat -c %Y $FILE2)`
if [ $DATE2 -gt $DATE1 ]; then
    echo "cp -f $FILE2 $FILE1"
#   cp -f $FILE2 $FILE1
fi

差不多了。清理你的代码并稍微调整一下这就是我得到的

#!/bin/bash
# select the two files (default option)
FILE1="/dir1/file1.binary"
FILE2="/dir1/file2.binary"
# You can also pass the two file names as arguments for the script
if [ $# -eq 2 ]; then
    FILE1=$1
    FILE2=$2
fi
# create the hash of the two files
HASH1="$(md5sum $FILE1 | sed -n -e 's/^.*= //p')"
HASH2="$(md5sum $FILE2 | sed -n -e 's/^.*= //p')"
# get the dates of last modification
DATE1="$(stat -f '%m%t%Sm' $FILE1 | cut -c 1-10)"
DATE2="$(stat -f '%m%t%Sm' $FILE2 | cut -c 1-10)"
# Uncomment to see the values
#echo $FILE1 ' = hash: ' $HASH1 ' date: ' $DATE1
#echo $FILE2 ' = hash: ' $HASH2 ' date: ' $DATE2
# compare the two hashes
if [ $HASH1 == $HASH2 ]; then
    # if the two hashes are the same, exit
    echo "the two files are identical"
    exit 0
fi
# compare the dates
if [ $DATE1 -gt $DATE2 ]; then
    # if FILE1 is newer than FILE2, replace FILE2 with FILE1
    cp $FILE1 $FILE2
    echo "${FILE2} was replaced by ${FILE1}"
elif [ $DATE1 -lt $DATE2 ]; then
    # else if FILE2 is newer than FILE1, replace FILE1 with FILE2
    cp $FILE2 $FILE1
    echo "${FILE1} was replaced by ${FILE2}"
else
    # else the files are identical
    echo "the two files are identical"
fi

你获取日期的方法是错误的，至少在我的机器上是错误的。所以我重写了。

您的哈希字符串错误。您有效地将字符串裁剪为前32个字符。通过使用sed，您实际上可以摆脱命令的第一部分，并简单地存储md5sum的结果。

正如HuStmpHrrr指出的那样，你还滥用了条件语句。

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