snippet

View script Copied!

Extract lines between start and end patterns from files or stdin. Like sed -n '/START/,/END/p' but easier to remember and with built-in trimming to exclude marker lines.

Useful when you need to pull a specific section from a log, config, or document without copying the boundary lines themselves. Works with regex patterns and handles cases where the end marker is optional (extract from start to EOF).

Quick start

$ snippet -s "BEGIN CERTIFICATE" -e "END CERTIFICATE" cert.pem
MIIBkTCB+wIJAKHHCgVZU1p0MA0GCSqGSIb3DQEBCwUAMBQxEjAQBgNVBAMMCWxv
Y2FsaG9zdDAeFw0yMDAxMDEwMDAwMDBaFw0zMDAxMDEwMDAwMDBaMBQxEjAQBgNV
...

Or pipe directly:

$ cat logfile.txt | snippet -s "Error:"

Common examples

Extract a section and trim the markers:

$ snippet -s "START CONFIG" -e "END CONFIG" -t 1 config.txt
database=prod
timeout=30

The -t 1 flag excludes the first and last line of the match (the marker lines themselves).

Pull everything from a marker to end of file:

$ snippet -s "=== SUMMARY ===" report.txt
=== SUMMARY ===
Total errors: 3
Total warnings: 12
Build time: 2m 15s

Extract from a piped log:

$ docker logs my-container | snippet -s "Stack trace:" -e "^$"
Stack trace:
  at handleRequest (/app/server.js:142:15)
  at processTicksAndRejections (node:internal/process:12:3)

The end pattern ^$ matches the first blank line after the start.

Trim only the start marker:

$ snippet -s "# BEGIN SECTION" -e "# END SECTION" -f 1 notes.md
Item 1
Item 2
Item 3
# END SECTION

The -f 1 flag excludes the first line only.

Pattern matching

Start and end patterns are passed to sed as regular expressions. Use literal strings for simple markers or regex patterns for more complex matching:

$ snippet -s "^Error:" -e "^[A-Z]" application.log

This extracts from lines starting with "Error:" up to the next line starting with a capital letter.

Patterns are case-sensitive by default (sed default behavior).

Trimming

Three flags control which matched lines are excluded:

-f N / --trim-first N -- drop the first N lines of the match
-l N / --trim-last N -- drop the last N lines of the match
-t N / --trim N -- drop the first and last N lines (shorthand for -f N -l N)

Trimming happens after matching, so the boundary lines are used to find the section but then optionally removed from output.

Reference

All options

Flag	Description
`-s, --start PATTERN`	Start pattern (required)
`-e, --end PATTERN`	End pattern (optional; if omitted, reads to EOF)
`-f, --trim-first N`	Exclude the first N lines of the matched snippet
`-l, --trim-last N`	Exclude the last N lines of the matched snippet
`-t, --trim N`	Exclude the first and last N lines of the matched snippet
`-h, --help`	Display help

Exit codes

Code	Meaning
0	Success
2	Usage error (missing required flag value, no start pattern provided, unknown option)

Dependencies

None -- uses only standard Unix utilities.