Shell脚本检查文件是否有改动

目的：检查某个文件夹及其子文件夹下的所有文件是否被改动。

思路：

1. 使用stat命令将所有文件的更改时间记录到文件A中。每个被扫描的文件在文件A中被记录为一行。

2. 然后定期检查所有文件的最新更改时间。并将最新的更改时间记录到一个新文件B中。与A一样，每一行会记录一个被扫描文件的最新更改时间。

3. 逐行比较文件A和文件B。若某行不一致，则说明该行所表示的被扫描文件有改动。将这一行打印出来。

#!/bin/bash
# 定时检查文件是否有更改，有更改就打印出更改的文件。

# scan the file tree
scanDir(){
  # one parameter
  for i in ` ls $1 | sed -e 's/ /\n/g' `;
  do
    # check if this is a dir.
    if [ -d $1/$i ];
    then
      # iterate to son dir.
      checkDir "$1/$i"
    else
      # print just for debug.
      echo "$1/$i"
    fi
  done
}

# check the second paremter
if [[ $2 =~ ^[0-9]+$ ]]
then
  sleep_time=$2
  echo "set period as $sleep_time seconds"
else
  sleep_time=5
  echo "default period is 5 seconds"
fi

# put all the scan results to one list.
for i in `scanDir $1`;
do
  index=$[ index+1 ]
  files[$index]=$i
  echo ${files[$index]}
done

echo =================
echo ${files[@]}
echo ================

# incase some the two files exist before our monitor begins. delete them first.
rm -f /tmp/stat.temp
rm -f /tmp/nstat.temp

while true
do
  if [ -e /tmp/stat.temp ]
  # if stat.temp exist, indicate that we collect all the change Infos of all files already and store them in stat.temp
  then
    for i in ${files[@]};
    do
      echo -ne $i >> /tmp/nstat.temp
      stat -x $i | grep Change >> /tmp/nstat.temp
    done
    diff /tmp/stat.temp /tmp/nstat.temp > /tmp/diff.temp
    if [ $? -eq 0 ]
    then
      # if the result of diff to diff.temp is 0, it shows that the two files are the same, so there is no change.
      echo "no file change"
    else
      # there are some files changed in this branch
      echo "below file(s) are changed:"
      cat /tmp/diff.temp | grep ">"
      patch /tmp/stat.temp /tmp/diff.temp
      rm /tmp/diff.temp
    fi
    rm /tmp/nstat.temp
    sleep $sleep_time
  else
    # first time, we should collect all the Infos of all files and store them.
    for i in ${files[@]};
    do
      echo collect $i
      echo -ne $i >> /tmp/stat.temp
      stat -x $i | grep Change >> /tmp/stat.temp
    done
    echo infos are collected
    sleep 2
  fi
done

缺点：

目前该方案没有考虑文件的增减带来的改变。Shell脚本里也可以实现Map，用Map的话，应该是可以实现更复杂的检测。