格式化字符串以在24小时内添加前导零

Question

我正在使用PowerShell的-match运算符和正则表达式\\b(Thu|Fri|Sat|Sun).([012]?[0-9][:]\\d{2})来获取日期和时间a重新启动应该发生。

样本数据：

Patching - Prod - Fri 2:00
Patching - Prod - Fri 22:00
Patching - Prod - Thu 22:00
Patching - Prod - Fri 22:00
Patching - Prod - Sat 18:00
Patching - Prod - Sun 2:00
Patching - Prod - Sun 00:00
Patching - Prod - Sat 2:00

$Rebootinfo = "Patching - Prod - Sat 2:00"

"$Rebootinfo" -match "\b(Thu|Fri|Sat|Sun).([012]?[0-9][:]\d{2})" | Out-Null

这很好用，但是我发现当时间是2:00 AM我会获得2:00并且我希望将02:00的前导零填充到该结果中，如果时间是午夜，则结果将是0而不是所需的00:00

我一直在尝试本文中的建议， 但没有成功。

"Prod - Sun 2:00" -match "\b(Thu|Fri|Sat|Sun).([012]?[0-9][:]\d{2})" | Out-Null

$a = $Matches[2]
$a.ToString("00:00")

返回错误找不到“ ToString”的重载和参数计数：“ 1”。

我这样做的目的是将数据传递到PowerShell中，以获取直到该重启时间为止的天数。 例如，如果在周六运行，则周日2 AM需要增加1天。

Answer 1

您不能在字符串上使用数字格式，因此您需要先将小时/分钟转换为int。 以下是一些示例：

#Convert 2:00 to 200 int-number and format it to 00:00-style -> 02:00.
#18:00 -> 1800 -> 18:00
"{0:00:00}" -f ([int]$a.Replace(":",""))

要么

#Capture hour and minutes in their own groups
"Prod - Sun 2:00" -match "\b(Thu|Fri|Sat|Sun).([012]?[0-9])[:](\d{2})" | Out-Null
#Format 00 only works with digits, so convert to int
"{0:00}:{1:00}" -f [int]$Matches[2], [int]$Matches[3]

或者，您可以将其解析为DateTime并转换回具有正确格式的字符串（如果需要，也可以使用DateTime对象）。

$date = [datetime]::ParseExact($Matches[0], "ddd H:mm", [cultureinfo]::InvariantCulture)
$date.ToString("ddd HH:mm", [cultureinfo]::InvariantCulture)

Answer 2

您可以这样做：

"Prod - Sun 2:00" -match "\b(Thu|Fri|Sat|Sun).([012]?[0-9][:]\d{2})" | Out-Null
$a = $Matches[2]
$ts = [TimeSpan]::Parse($a)
$formatted = $ts.ToString("c").Substring(0, 5)
$formatted

它为$formatted输出02:00 。

Answer 3

您的帖子似乎没有问题（目标，但没有问题）。 因此，我猜您的问题是“为什么正则表达式不返回'02：00AM'”？

由于源字符串在2之前不包含零，因此您将无法获得源字符串中不包含零的匹配项。 您需要将其添加为单独的步骤。

通过使用.NET的内置日期时间解析，可以避免一些麻烦： [datetime]::parseexact 。 不幸的是，如果星期日不是当天，ParseExact无法处理诸如“ Sun 2:00 AM”之类的字符串，因此需要一些额外的工作。 这是一些相同的示例代码。

$Rebootinfo = "Patching - Prod - Thu 2:00AM"

$splitUp = $Rebootinfo -split "\b(Thu|Fri|Sat|Sun)"
# $splitUp[-1] now contains time and $splitUp[-2] contains day of week

$cult = [Globalization.CultureInfo]::InvariantCulture
try {
   $rebootTime = [datetime]::parseexact( $splitUp[-1], " h:mmtt", $cult)
} catch {
   # put your own error handling here
   throw "Date time parse failed"
}

$weekDayToWeekDayNumber = @{Sun=0;Mon=1;Tue=2;Wed=3;Thu=4;Fri=5;Sat=6}
$rebootWeekDayNumber = $weekDayToWeekDayNumber[$splitUp[-2]]
$todayWeekDayNumber = $weekDayToWeekDayNumber[[datetime]::today.DayOfWeek.tostring().substring(0,3)]
# This calculation fails if the reboot day of the week is same as current
# day of week and reboot time is before current time. However I'm guessing 
# this won't be a problem because if this
# happens you've already missed the boot or the boot is almost a week away.
# Assuming the later: since you only have days of the week (and not dates) 
# I'm guessing that
# boots almost a week away aren't a concern. The reason is that if you 
# handle boots almost a
# week away, there's no guarantee (that I see) that the boot won't be a 
# little more than a week away (since you don't know exactly when the boot 
# is, hence the script). And if boots can be more than a week away you won't 
# be able to distinguish between boots this week and boots next week (since
# you only have the day of the week).
# However if this is a problem, just compare $rebootTime to [datetime]::now
# and if less, then add 7 more days to $rebootTime.
$rebootTime = $rebootTime.AddDays( ($rebootWeekDayNumber - $todayWeekDayNumber + 7) % 7)

write-host Amount of time till reboot ($rebootTime - [datetime]::now)