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Bug: CloudWatch CSV Export Feature Produces Malformed Output

0

Description

When using the "Export displayed results" feature to export data as CSV, the output contains formatting errors that make the CSV invalid.

Steps to Reproduce

  1. Generate a log message that begins with a dash and includes a newline character: - using env: export GIN_MODE=release\n
  2. View this log message in CloudWatch
  3. Use the "Export displayed results" feature to export as CSV

Actual Result

The log entry is incorrectly formatted in the CSV output with a single quote placed before the double quotes:

'"- using env:	export GIN_MODE=release
"

Expected Result

The CSV should properly escape or format the log message.

"- using env:	export GIN_MODE=release
"

Technical Context (Guess)

The single quote (') appears to be an attempt to ensure numeric values display correctly in Excel, assuming the - is being mistaken for a negative number prefix?

However, this formatting rule is being incorrectly applied outside the double quotes that encapsulate the field, breaking the CSV format.

Impact

The invalid formatting prevents the CSV file from being properly processed by standard CSV parsers.

Topics
Management & Governance
Tags
Amazon CloudWatchAmazon CloudWatch Logs
Language
English

asked a year ago113 views

1 Answer
0

This definitely looks like a formatting quirk tied to how CloudWatch handles CSV exports — especially when log entries start with a dash or newline. I’ve seen similar behavior where the export prepends a single quote (') to avoid Excel misinterpreting values as formulas or numbers (e.g., anything starting with -, =, or +).

Unfortunately, in this case, it’s applying that fix outside the quoted field, which ends up breaking proper CSV structure. It’s not just annoying — it really does mess with parsers that expect valid escaping.

Until AWS adjusts this behavior, a quick workaround might be to:

Open the file in a raw text editor instead of Excel

Strip the extra single quotes via script or sed/awk

Or manually reformat multiline entries before ingesting them downstream

But yeah — this feels like something that should be patched at the export level. You’re not imagining it, and your example helps illustrate the edge case really well.

answered a year ago

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