[PowerShell每日技巧]获取昨天的日期、时间-比如零点(20131226)

DAIC

Getting relative dates (like yesterday or one week ahead) is easy once you know the Add…() methods every DateTime object supports. This would give you yesterday:

1. $today = Get-Date
   
2. $yesterday = $today.AddDays(-1)
   
3. $yesterday

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$yesterday will be exactly 24 hours before now. So what if you would like yesterday, but at a given time? Let's say, yesterday at midnight?

If you really want today at midnight, things are easy:

1. $todayMidnight = Get-Date -Hour 0 -Minute 0 -Second 0
   
2. $todayMidnight

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And if you want another date with a given time, use Get-Date again to override the parts of the date you need. This is yesterday at midnight:

1. $today = Get-Date
   
2. $yesterday = $today.AddDays(-1)
   
3. $yesterday | Get-Date -Hour 0 -Minute 0 -Second 0

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http://powershell.com/cs/blogs/tips/archive/2013/12/26/getting-yesterday-s-date-at-midnight.aspx