AWS S3上に保存されているファイルの更新タイムスタンプチェック ref: https://qiita.com/na0AaooQ/items/a6a209742bbe073ed12e

file0.txt

$ aws s3 sync s3://test-web-data-store/test/ /home/ec2-user/
download: s3://test-web-data-store/test/test2.txt to ./test2.txt
download: s3://test-web-data-store/test/test.txt to ./test.txt
$

file1.txt

{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": ["s3:ListAllMyBuckets"],
      "Resource": "arn:aws:s3:::*"
    },
    {
      "Effect": "Allow",
      "Action": [
        "s3:ListBucket",
        "s3:GetBucketLocation"
      ],
      "Resource": "arn:aws:s3:::test-web-data-store"
    },
    {
      "Effect": "Allow",
      "Action": [
        "s3:PutObject",
        "s3:GetObject",
        "s3:DeleteObject"
      ],
      "Resource": "arn:aws:s3:::test-web-data-store/*"
    }
  ]
}

file2.txt

$ date
Sun Dec 21 17:13:13 UTC 2014
$ aws s3 ls s3://test-web-data-store/test/
2014-12-21 16:53:39          0
$

$ date > /tmp/test.txt
$

$ aws s3 cp /tmp/test.txt s3://test-web-data-store/test/
upload: ../../tmp/test.txt to s3://test-web-data-store/test/test.txt
$

$ aws s3 ls s3://test-web-data-store/test/
2014-12-21 16:53:39          0
2014-12-21 17:14:05         29 test.txt
$

file3.txt

$ rm -f /tmp/test.txt
$ ll /tmp/test.txt
ls: cannot access /tmp/test.txt: No such file or directory
$

file4.txt

$ aws s3 ls s3://test-web-data-store/test/ | grep 'test.txt' | awk '{print $1,$2}'
2014-12-21 17:14:05
$

file5.txt

$ vi s3_download_test.sh

file6.txt

$ chmod 754 s3_download_test.sh

file7.txt

$ chmod 754 s3_download_test.sh

file8.txt

$ aws s3 ls s3://test-web-data-store/test/test.txt
2014-12-21 17:14:05         29 test.txt
$

$ ./s3_download_test.sh
not diff [s3://test-web-data-store/test//test.txt]
$

$ aws s3 ls s3://test-web-data-store/test/test.txt
2014-12-21 17:14:05         29 test.txt
$
$ ll /tmp/test.txt
ls: cannot access /tmp/test.txt: No such file or directory
$

file9.txt

$ date >> test.txt
$ date >> test.txt
$

$ aws s3 cp test.txt s3://test-web-data-store/test/
upload: ./test.txt to s3://test-web-data-store/test/test.txt
$
$ rm test.txt
$ ll test.txt
ls: cannot access test.txt: No such file or directory
$ ll /tmp/test.txt
ls: cannot access /tmp/test.txt: No such file or directory
$

$ aws s3 ls s3://test-web-data-store/test/test.txt
2014-12-21 17:37:49         58 test.txt
$

$ ./s3_download_test.sh
diff [s3://test-web-data-store/test/test.txt]
aws s3 cp s3://test-web-data-store/test/test.txt /tmp/
download: s3://test-web-data-store/test/test.txt to ../../tmp/test.txt
$

$ ll /tmp/test.txt
-rw-rw-r-- 1 ec2-user ec2-user 58 Dec 21 17:45 /tmp/test.txt
$

s3_download_test.sh

#!/bin/sh

S3_BUCKET="s3://test-web-data-store/test"
S3_CHECK_FILE="test.txt"

OLD_TIMESTAMP_FILE="/tmp/old_file_timestamp.txt"
NEW_TIMESTAMP_FILE="/tmp/new_file_timestamp.txt"

DOWNLOAD_DIR="/tmp"

if [ -f ${NEW_TIMESTAMP_FILE} ] ; then
        mv ${NEW_TIMESTAMP_FILE} ${OLD_TIMESTAMP_FILE}
fi

# S3バケット上のファイルのタイムスタンプを取得
aws s3 ls ${S3_BUCKET}/ | grep "${S3_CHECK_FILE}" | awk '{print $1,$2}' > ${NEW_TIMESTAMP_FILE}

if [ -f ${OLD_TIMESTAMP_FILE} ] ; then

        DIFF_COUNT=`diff ${NEW_TIMESTAMP_FILE} ${OLD_TIMESTAMP_FILE} | wc -l`

        if [ ${DIFF_COUNT} -ge 1 ] ; then

                echo "diff [${S3_BUCKET}/${S3_CHECK_FILE}]"
                echo "aws s3 cp ${S3_BUCKET}/${S3_CHECK_FILE} ${DOWNLOAD_DIR}/"
                aws s3 cp ${S3_BUCKET}/${S3_CHECK_FILE} ${DOWNLOAD_DIR}/

        else

                echo "not diff [${S3_BUCKET}/${S3_CHECK_FILE}]"

        fi
fi