1

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

我创建了一个简单的脚本，但我需要您的帮助才能使其正常运行：

#!/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（至少如果两个文件相同），但如果一个文件已被修改，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？

谢谢

非常感谢大家的帮助。这是脚本现在的样子。QNAP 的 QTS 也有通知，但如果在其他地方运行或不需要，可以将其取出。

#!/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
4

3 回答 3

4

我还将建议重构它，以简化代码并节省 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

您可能会发现一些有用的东西。

  • 这避免了对每个文件计算 md5。虽然对于像你这样的小文件比较总和可能很好，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，因为您有cmp可用的命令。最好养成编写代码的习惯，以便在您为下一个项目回收它时使用较少的修改。
  • if语句运行一个命令，通常是或[，[[但它可以是任何命令。在这里，我们在一个中运行cmp，以便我们可以轻松地检查结果。cpif
  • 这不再使用stat了。虽然您可能永远不会超越 Linux，但始终牢记可移植性总是一个好主意，如果您可以使脚本可移植，那就太好了。
  • 这不是bash脚本。你的脚本也不是——如果你用 调用你的脚本/bin/sh，那么你就处于 POSIX 兼容模式，这已经使它比你想象的更便携。:-)
  • 缩进有帮助。您可能希望将它用于您自己的脚本，以便您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。
于 2015-08-12T23:00:37.217 回答
0

像下面这样更简单的东西呢？

#!/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
于 2015-08-12T21:57:02.007 回答
-1

差不多好了。清理你的代码并在这里稍微调整一下就是我得到的

#!/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

你获取日期的方式是错误的，至少在我的机器上是这样。所以我重写了它。

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.

正如 HuStmpHrrr 指出的那样，您还滥用了条件语句。

剩下的就是化妆品了。

于 2015-08-12T22:41:31.193 回答