sed

name	sed
description	Guide for using the sed() tool to read, search, and transform files. Use when the user asks about sed commands, sed syntax, or needs help with text processing via sed.

sed() Guide

sed(path, cmds, inplace=False, quiet=False, linenums=False, as_dict=False)

Runs sed on a file. Non-destructive by default (prints to stdout). Use inplace=True to modify the file.

Parameters

• quiet=True — like sed -n; essential when using p, otherwise matched lines are doubled
• inplace=True — like sed -i ''; modifies file, returns nothing
• as_dict — returns {'success': ...} or {'error': ...}
• linenums=True — numbers output lines; with inplace, shows the modified file with line numbers. Cannot combine with quiet.

Examples

sed('f.py', '3,5p', quiet=True)              # read a range
sed('f.py', '/start/,/end/p', quiet=True)    # read between patterns
sed('f.py', 's/old/new/g')                   # preview substitution
sed('f.py', 's/old/new/g', inplace=True)     # apply it
sed('f.py', 's/old/new/g', inplace=True, linenums=True)  # apply and see result
sed('f.py', '/DEBUG/d', inplace=True)        # delete matching lines
sed('f.py', r'3i\
NEW LINE')                                   # insert before line 3
sed('f.py', r's/\(.*\)/[\1]/')              # capture groups (BRE: escaped parens)

Gotchas

• quiet=True for reading — without it, p duplicates matched lines.
• Preview then apply — run without inplace first, then re-run with inplace=True.
• BRE by default — parens must be escaped: \(…\), \1.
• macOS sed — i/a/c require backslash-newline; = takes only a single address, not a range.
• | works as delimiter — unlike ex, s|old|new| is fine.