Shell脚本替换JSON中字符串为证书内容时sed报错问题

Let's break down what's causing this error and how to fix it properly:

Why the Error Happens #

The error sed: 1: "s/ORDERER_CA_CERT/----- ...": bad flag in substitute command: 't' occurs because:

• By default, sed uses / as the delimiter for its substitute command (s/search/replace/flags).
• Your certificate content likely contains characters that interfere with this delimiter, or gets misinterpreted as a sed command flag (in this case, a t character in your cert text was being treated as a jump flag instead of part of the certificate).
• Additionally, unescaped special characters like & or backslashes in the certificate will cause sed to misprocess the substitution.

Step-by-Step Solution #

1. Properly Process the Certificate Content #

First, convert the multi-line certificate into a JSON-compatible single line, and escape characters that would break sed:

# Read the cert, convert newlines to JSON-friendly \\n, escape backslashes and & for sed
CERT=$(cat cert.crt | awk '{printf "%s\\n", $0}' | sed 's/\\/\\\\/g; s/&/\\&/g')

• awk '{printf "%s\\n", $0}': Appends an escaped newline (\\n) to each line of the cert, making it valid for JSON string values.
• sed 's/\\/\\\\/g; s/&/\\&/g': Escapes backslashes (so sed doesn't misinterpret them) and ampersands (which sed treats as a reference to the matched search string).

2. Use a Non-Conflicting Delimiter in sed #

Instead of the default / delimiter, pick a character that won't appear in your certificate (like # or |):

# Replace _CERT_ in the template with the processed cert, output to test.json
sed "s#_CERT_#$CERT#g" template.json > test.json

Using # as the delimiter avoids conflicts with any / characters that might be present in your certificate (uncommon, but possible in some PEM formats).

Verify the Result #

Open test.json and check that the certificate content is a valid JSON string:

• It should be enclosed in double quotes.
• Newlines from the original cert are represented as \n.
• No stray characters that would break JSON parsing.

内容的提问来源于stack exchange，提问作者Rohit Khatri