使用sed替换换行分隔的大括号失败，寻求可行解决方案

Got it, let's work through this sed problem you're stuck on. The biggest pain here is targeting only those newline-separated curly brace blocks without accidentally touching all the other lines that start with {—I totally get why generic fixes fell flat.

Let's Start with a Precise Sed Script #

Assuming you're trying to replace entire blocks where { is on its own line, followed by any content, and ending with } on its own line (like the example below), here's a script that will only target those specific blocks:

# First, store your replacement text in a variable to avoid quoting headaches
REPLACEMENT="Doesn't matter about \n I've tried this : but doesn't work. I've tried other strange solutions but don't work as well because in the file there are a lot of others rows that start with { . Could you please suggest some solution?"

# Run the sed command
sed -E ':loop; /^{$/{N; /\n}$/!b loop; s/.*\n.*$/'"$REPLACEMENT"'/}' yourfile.txt

How This Works (Breakdown) #

Let's unpack what each part does so you can tweak it if needed:

• :loop: Creates a label for looping through lines until we find the closing }
• /^{$/: Matches lines that contain only { (so it ignores lines like { "data": 123 } that start with { but have other content)
• N: Reads the next line into the pattern space (combines the current line with the next)
• /\n}$/!b loop: If the combined lines don't end with a newline followed by }, jump back to the loop label to read another line
• s/.*\n.*$/'"$REPLACEMENT"'/: Replaces the entire matched block (from the opening { to closing }) with your desired text

Tweaks for Different Scenarios #

If your target blocks don't have {/} on their own lines (e.g., { is at the start of a line with other text, but the closing } is on its own line), adjust the match pattern:
Change /^{$/ to /^{/ to match any line starting with {, but keep the rest of the script the same. Just note this might catch more blocks, so test it on a copy of your file first!

In-File Editing #

To modify your file directly (instead of printing to stdout), add the -i flag (GNU sed):

sed -i -E ':loop; /^{$/{N; /\n}$/!b loop; s/.*\n.*$/'"$REPLACEMENT"'/}' yourfile.txt

For BSD sed (common on macOS), use -i '' instead:

sed -i '' -E ':loop; /^{$/{N; /\n}$/!b loop; s/.*\n.*$/'"$REPLACEMENT"'/}' yourfile.txt

Test First! #

Always run the command without -i first to verify it's only replacing the blocks you want—no one wants to accidentally mess up a large file!

内容的提问来源于stack exchange，提问作者ClaudioM