如何更改sed中的日期格式? [英] How to change date format in sed?

问题描述

假设我想通过 date 命令将时间戳中的日期转换为另一种格式.在控制台中，我会说 date -d@ 但我碰巧想对文本文件中的许多字段执行此操作.

Say I want to convert a date in timestamp to another format through the date command. In console I would say date -d@<timestamp> but I happen to want to do this to many fields in a text file.

使用 e 在 sed 中执行(sed (GNU sed) 4.2.2，实际上)我是说:

Using the e to execute in sed (sed (GNU sed) 4.2.2, actually) I am saying:

$ echo 1449158360 | sed -r 's#.*([0-9]{10}).*#date -d@1 "+%Y";#e'
2015

效果很好，不错！

现在我创建了一个虚拟文件myfile:

Now I created a dummy file myfile:

my timestamp is 1449158360 but also I wonder what date was 1359199960.

我想将其替换为相同但具有时间戳的相对年份:

Which I would like to have replaced to the same but having the relative year of the timestamps:

my timestamp is 2015 but also I wonder what date was 2013.

但是，如果我尝试运行与上面相同的命令，则会失败:

However, if I try to run the same command as above it fails:

$ sed -r 's#([0-9]{10})#date -d@"1" "+%Y";#e' myfile
sh: my: command not found
sh: but: command not found

因为 sed 将第一个单词解释为要执行的内容.

Because sed interprets the first words as something to execute.

显然，如果我只获取这些数据而没有其他任何东西，它就可以工作:

Obviously it works if I just fetch these data and nothing else:

$ sed -r 's#.*([0-9]{10}).*#date -d@"1" "+%Y";#ge' myfile
2015

所以我想知道:我应该怎么做才能针对 sed 中捕获的组调用 date 并用它替换文本，考虑到它被其他必须保留的文本包围原封不动?

So I wonder: what should I do to call date against captured groups in sed and replace text with it, considering it is surrounded by other text that have to remain untouched?

推荐答案

e switch in sed 替换应用 sh -c 到不匹配的文本以及从这个命令明显:

e switch in sed substitute applies sh -c to unmatched text as well as evident from this command:

echo 'a 1449158360' | sed -r 's#([0-9]{10})#date -d@1 "+%Y";#e'
sh: a: command not found 

所以即使我们只匹配 1449158360 但 sh -c 正在 a 1449158360 上运行.

So even though we are matching only 1449158360 but sh -c is being run on a 1449158360.

由于 sed 中没有非贪婪和前瞻正则表达式，这个解决方法正则表达式可能看起来很疯狂，但这就是您如何像您的问题一样为来自文件的多个匹配输入运行它:

Due to absence of non-greedy and lookaheads regex in sed this workaround regex might appear crazy but this is how you can run it for multiple matching input from file as in your question:

sed -r 's#(([^0-9][0-9]{0,9})*)([0-9]{10})(([0-9]{0,9}[^0-9])*)#printf "%s%s%s" "1" $(date -d@3 "+%Y") "4";#ge' file

基本上我们在这个正则表达式中匹配10-digits.

Basically we are matching <before>10-digits<after> in this regex.

输出:

my timestamp is 2015 but also I wonder what date was 2013.

为了阐明所使用的正则表达式，我创建了这个演示.

To clarify the regex used I have created this demo.

这绝不是 e 模式问题的通用解决方案，请将其视为基于正则表达式的解决方法.

By no means this is a generic solution to e mode issue, treat it as a regex based workaround.

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