写入成功后删除现有文件

Question

我正在python脚本中执行每日数据库转储，我正在寻找最有效的python方法，以便仅在最近的文件成功写入后才删除当前文件，即仅在backup-13-11-2019成功创建后才删除backup-12-11-2019.sql

Answer 1

您可以使用try:...except:...esle:作为以下代码。

import datetime
import os
now = datetime.datetime.utcnow()
try:
    pg_dumpall('-h', DB_HOST, '-U', DB_USERNAME, '-p', DB_PORT, _out=BACKUP_FOLDER + 'backup-' + str(now.day) + '-' + str(now.month) + '-' + str(now.year) + '.sql')
except Exception as e:
    print(e)
else:
    previous_day = now - datetime.timedelta(days=1)
    os.remove(BACKUP_FOLDER + 'backup-' + str(now.day - 1) + '-' + str(now.month) + '-' + str(now.year) + '.sql')

如果pg_dumpall未启动并发生Exception，它将删除以前的备份文件

最好的尊重

Answer 2

来自DBA StackExchange

    pg_dumpall -U pg_user > /tmp/tmp.txt
    DUMP_STATUS=$?
    echo "Dump status: $DUMP_STATUS" > /tmp/status.txt

和SO: Get return value

    subprocess.check_output([SCRIPT, "-d", date], shell=True).

我们能够想出一些东西来运行你想要运行的命令，同时检查它的返回值。

    output = subprocess.check_output(['pg_dumpall', '-h', DB_HOST, '-U', DB_USERNAME, '-p', DB_PORT], stdout=outfile)
    if output == 0:
        print("Success")
        os.remove(oldfile)
    else:
        print("Failure")