blocks|key|359673|text|我认为这应该是有效的，无论你运行它的频率和时间是多少……|type|unstyled|depth|inlineStyleRanges|entityRanges|data|359674|date+-d+"yesterday+13:00"+'%2B%25Y-%25m-%25d'|code-block|syntax|javascript|359675|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I think this should work, irrespective of how often and when you run it ... 

<pre><code>date -d "yesterday 13:00" '+%Y-%m-%d'
</code></pre>

blocks|key|141827|text|这也应该是可行的，但可能太多了：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|141828|date+-d+@$((+$(date+%2B"%25s")+-+86400))+%2B"%25Y-%25m-%25d"|code-block|syntax|javascript|141829|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This should also work, but perhaps it is too much:

<pre><code>date -d @$(( $(date +"%s") - 86400)) +"%Y-%m-%d"
</code></pre>

blocks|key|359758|text|如果您确定脚本在一天中的第一个小时运行，您可以简单地执行以下操作|type|unstyled|depth|inlineStyleRanges|entityRanges|data|359759|++date+-d+"12+hours+ago"+'%2B%25Y-%25m-%25d'|code-block|syntax|javascript|359760|顺便说一句，如果脚本每天在00:35运行(通过crontab?)您应该问问自己，如果DST更改在那个小时内发生，会发生什么；脚本不能运行，在某些情况下会运行两次。不过，在这方面，cron的现代实现是quite+clever的。|offset|length|style|CODE|359761|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/13195999/daylight-savings-and-cron^0|0|0|2H|4|2R|C|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@$I|X|J|Y|K|L]]|9|@$I|Z|J|10|1|11]]|A|$]]|$1|M|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]]]

If you are certain that the script runs in the first hours of the day, you can simply do

<pre><code> date -d "12 hours ago" '+%Y-%m-%d'
</code></pre>

BTW, if the script runs daily at 00:35 (via crontab?) you should ask yourself what will happen if a DST change falls in that hour; the script could not run, or run twice in some cases. Modern implementations of <code>cron</code> are <a href="https://stackoverflow.com/questions/13195999/daylight-savings-and-cron">quite clever</a> in this regard, though.

blocks|key|141960|text|这里提供了一个同样适用于Solaris和AIX的解决方案。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|141961|可以通过操作时区来更改几个小时的时钟。由于夏令时的原因，24小时前可以是今天也可以是前天。|141962|你确定昨天已经是20或30个小时前了。哪个？好吧，最近的一个不是今天的。|141963|echo+-e+"$(TZ=GMT%2B30+date+%2B%25Y-%25m-%25d)\n$(TZ=GMT%2B20+date+%2B%25Y-%25m-%25d)"+%7C+grep+-v+$(date+%2B%25Y-%25m-%25d)+%7C+tail+-1|code-block|syntax|javascript|141964|回显命令中使用的-e参数是bash所必需的，但不适用于ksh。在ksh中，您可以使用不带-e标志的相同命令。|141965|当您的脚本将在不同的环境中使用时，您可以使用#!/bin/ksh或#!/bin/bash启动脚本。您还可以将\n替换为换行符：|141966|echo+"$(TZ=GMT%2B30+date+%2B%25Y-%25m-%25d)
$(TZ=GMT%2B20+date+%2B%25Y-%25m-%25d)"+%7C+grep+-v+$(date+%2B%25Y-%25m-%25d)+%7C+tail+-1|141967|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|U|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|V|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|W|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|H|7|Y|8|@]|9|@]|A|$I|J]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

Here a solution that will work with Solaris and AIX as well.

Manipulating the Timezone is possible for changing the clock some hours.
Due to the daylight saving time, 24 hours ago can be today or the day before yesterday.

You are sure that yesterday is 20 or 30 hours ago. Which one? Well, the most recent one that is not today.

<pre><code>echo -e "$(TZ=GMT+30 date +%Y-%m-%d)\n$(TZ=GMT+20 date +%Y-%m-%d)" | grep -v $(date +%Y-%m-%d) | tail -1
</code></pre>

The -e parameter used in the echo command is needed with bash, but will not work with ksh.
In ksh you can use the same command without the -e flag.

When your script will be used in different environments, you can start the script with #!/bin/ksh or #!/bin/bash. You could also replace the \n by a newline:

<pre><code>echo "$(TZ=GMT+30 date +%Y-%m-%d)
$(TZ=GMT+20 date +%Y-%m-%d)" | grep -v $(date +%Y-%m-%d) | tail -1
</code></pre>

blocks|key|141992|text|您可以使用|type|unstyled|depth|inlineStyleRanges|entityRanges|data|141993|date+-d+"30+days+ago"+%2B"%25d/%25m/%25Y"|code-block|syntax|javascript|141994|要获取30天前的日期，同样可以将30替换为x天数|141995|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

you can use

<pre><code>date -d "30 days ago" +"%d/%m/%Y"
</code></pre>

to get the date from 30 days ago, similarly you can replace 30 with x amount of days

blocks|key|142042|text|您可以使用：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|142043|date+-d+"yesterday+13:55"+'%2B%25Y-%25m-%25d'|code-block|syntax|javascript|142044|或者你想检索的任何时间都会被bash检索到。|142045|对于月份：|142046|date+-d+"30+days+ago"+'%2B%25Y-%25m-%25d'|142047|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|S|8|@]|9|@]|A|$E|F]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

You can use:

<pre><code>date -d "yesterday 13:55" '+%Y-%m-%d'
</code></pre>

Or whatever time you want to retrieve will retrieved by bash.

For month:

<pre><code>date -d "30 days ago" '+%Y-%m-%d'
</code></pre>

I have a shell script that runs on Linux and uses this call to get yesterday's date in <code>YYYY-MM-DD</code> format:

<pre><code>date -d "1 day ago" '+%Y-%m-%d'
</code></pre>

It works most of the time, but when the script ran yesterday morning at <code>2013-03-11 0:35 CDT</code> it returned <code>"2013-03-09"</code> instead of <code>"2013-03-10"</code>.

Presumably daylight saving time (which started yesterday) is to blame. I'm guessing the way <code>"1 day ago"</code> is implemented it subtracted 24 hours, and 24 hours before <code>2013-03-11 0:35 CDT</code> was <code>2013-03-09 23:35 CST</code>, which led to the result of <code>"2013-03-09"</code>.

So what's a good DST-safe way to get yesterday's date in bash on Linux?

Get yesterday's date in bash on Linux, DST-safe

Solaris

Linux

我有一个运行在Linux上的shell脚本，它使用这个调用来获取YYYY-MM-DD格式的昨天的日期：date -d "1 day ago" '+%Y-%m-%d'它在大多数情况下都是有效的，但是当脚本昨天早上在2013-03-11 0:35 CDT上运行时，它返回了"2013-03-09"而不是"2013-03-10...

问在Linux，DST-safe上获取昨天的日期
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