我如何将一些文本附加到没有临时文件的管道中 [英] How do i append some text to pipe without temporary file

问题描述

我正在尝试从一个程序有多个版本的目录中获取最大版本号

I am trying to get the max version number from a directory where i have several versions of one program

例如，如果ls的输出是

for example if output of ls is

something01_1.sh
something02_0.1.2.sh
something02_0.1.sh
something02_1.1.sh
something02_1.2.sh
something02_2.0.sh
something02_2.1.sh
something02_2.3.sh
something02_3.1.2.sh
something.sh

我正在获得具有以下内容的最大版本号-

I am getting the max version number with the following -

ls somedir | grep some_prefix | cut -d '_' -f2 | sort -t '.' -k1 -r | head -n 1

现在，如果同时我想用系统中已有的版本号检查它，那么最好的方法是什么...

Now if at the same time i want to check it with the version number which i already have in the system, whats the best way to do it...

在bash中，我可以正常工作(如果当前版本为2.5)

in bash i got this working (if 2.5 is the current version)

(ls somedir | grep some_prefix | cut -d '_' -f2; echo 2.5) | sort -t '.' -k1 -r | head -n 1

还有其他正确的方法吗?

is there any other correct way to do it?

在上面的示例中，some_prefix是something02.

In the above example some_prefix is something02.

这里的实际问题是

(ls smthing; echo more) | sort 

这是将两个命令/程序的输出合并到第三个命令的最佳方法.

is it the best way to merge output of two commands/program for piping into third.

推荐答案

我找到了解决方案.看来最好的方法是使用流程替换.

I have found the solution. The best way it seems is using process substitution.

cat <(ls smthing) <(echo more) | sort

以我的版本示例

cat <(ls somedir | grep some_prefix | cut -d '_' -f2) <(echo 2.5) | sort -t '.' -k1 -r | head -n 1

为了将来的读者的利益，我建议-请放弃一线诱饵，并使用glob作为 chepner 建议.

for the benefit of future readers, I recommend - please drop the lure of one-liner and use glob as chepner suggested.

在超级用户上提出了几乎类似的问题.

Almost similar question is asked on superuser.

有关流程替换的更多信息.

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