sed:同时就地替换，并打印出更改的行? [英] sed: simultanous in-place replacement, and printout of changed lines?

问题描述

说我有这个文件:

cat > test.txt <<EOF
line one word
line two word
line three word
line one two word
EOF

假设我想将文件 test.txt<中的所有单词two"替换为TWO"，inline 就地/代码>.

And let's say I want to replace all of the words 'two' with 'TWO', inline in-place in the file test.txt.

现在，我所做的通常是构建一个预览"(使用 -n 不打印行，然后使用 /p - 仅打印匹配的行):

Now, what I do, is usually construct a "preview" (with -n don't print lines, and then with /p - print matched lines only):

$ sed -n 's/two/TWO/gp' test.txt 
line TWO word
line one TWO word

... 然后我通常会执行实际的就地替换(使用 -i，不使用 /p):

... and then I usually execute the actual in-place replacement (with -i, and without /p):

$ sed -i 's/two/TWO/g' test.txt
$ cat test.txt 
line one word
line TWO word
line three word
line one TWO word

有没有办法让 sed 在文件中就地更改行，和从单个命令行将更改的行打印到标准输出?

Is there a way to get sed to both change lines in-place in a file, and print the changed lines to stdout, from a single command line?

推荐答案

在 Linux 上，您可能能够逃脱:

On Linux, you may be able to get away with:

sed -i '/two/{s/two/TWO/g; w /dev/stdout}' test.txt

在 BSD 系统(包括 Mac OS X)上，sed 对何时可以将操作组合到一行中的规则有点古怪，我不得不使用:

On BSD systems (including Mac OS X), where the sed has slightly eccentric rules about when you can combine actions onto a single line, I had to use:

sed -i '/two/{s/two/TWO/g; w /dev/stdout
       }' test.txt

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