fedit — Fast File Editor for the Terminal

A zero-dependency CLI tool for surgical file edits from the command line. No interactive editors. No sed/awk gymnastics. Just simple, predictable operations with built-in verification.

Built for sysadmins, DevOps engineers, and anyone who scripts config changes.

go install github.com/amalexico/fedit@latest

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Why fedit?

• One binary, zero dependencies — pure Go, runs everywhere
• 17 language mappers — see the structure of any file before editing
• -v flag — verify every mutation before moving on
• Line-aware — no regex surprises, no "which match did it hit?"
• Safe — no in-place unless you say so, never touches files you did not name

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Install

Go install (recommended):

go install github.com/amalexico/fedit@latest

Or download the binary from GitHub Releases and put it in your PATH.

Verify:

fedit -file /etc/hostname -op show

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Quick Start

# See what is in a file
fedit -file config.yaml -op show

# See just lines 10-25
fedit -file config.yaml -op show -line 10 -end 25

# Find every line containing "timeout"
fedit -file config.yaml -op find -match "timeout"

# See the structure of a Go file
fedit -file main.go -op map -lang go

# Replace line 42 with new content
fedit -file config.yaml -op replace -line 42 -end 42 -text "timeout: 60s" -v

# Insert a line after every occurrence of "server {"
fedit -file nginx.conf -op insertafter -match "server {" -text "    include security.conf;" -v

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All Operations

show — Display file contents

# Entire file
fedit -file app.conf -op show

# Lines 50-75 only
fedit -file app.conf -op show -line 50 -end 75

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find — Search for lines matching a substring

# Find all lines containing "ERROR"
fedit -file /var/log/app.log -op find -match "ERROR"

# Output includes context lines and occurrence numbers
# Use -nth to target a specific match in other operations

Pro tip: Run find first to get line numbers, then use replace or delete with exact lines.

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insert — Insert content after a line number

# Insert a comment after line 1
fedit -file script.sh -op insert -line 1 -text "# Added by deploy script" -v

# Insert multiple lines from a file
fedit -file config.yaml -op insert -line 10 -textfile extra-config.yaml -v

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insertafter — Insert after a matching line (RECOMMENDED)

# Add a firewall rule after the matching comment
fedit -file iptables.rules -op insertafter -match "# Custom rules" -text "-A INPUT -p tcp --dport 8080 -j ACCEPT" -v

# Target the 2nd occurrence
fedit -file nginx.conf -op insertafter -match "server {" -nth 2 -text "    listen 8443 ssl;" -v

# Target the last occurrence
fedit -file docker-compose.yml -op insertafter -match "volumes:" -nth -1 -text "      - /data:/data" -v

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insertbefore — Insert before a matching line (RECOMMENDED)

# Add a header before the first route definition
fedit -file routes.rb -op insertbefore -match "get '/'" -text "  # === Public Routes ===" -v

# Insert a dependency before the closing bracket
fedit -file package.json -op insertbefore -match "}" -nth -1 -textfile new-deps.txt -v

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replace — Replace a line range with new content

# Replace a single line
fedit -file config.ini -op replace -line 15 -end 15 -text "max_connections = 200" -v

# Replace lines 30-35 with content from a patch file
fedit -file server.conf -op replace -line 30 -end 35 -textfile patched-block.txt -v

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replaceall — Global find-and-replace

# Change all occurrences of old domain to new
fedit -file nginx.conf -op replaceall -match "old.example.com" -text "new.example.com" -v

# Update a version string everywhere
fedit -file Makefile -op replaceall -match "1.1.0" -text "1.2.0" -v

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delete — Remove lines

# Delete a single line
fedit -file hosts -op delete -line 12 -end 12 -v

# Delete a block (lines 40-55)
fedit -file config.yaml -op delete -line 40 -end 55 -v

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write — Create or overwrite a file

# Create a new file
fedit -file /tmp/note.txt -op write -text "Deployment started" -v

# Write multi-line content from another file
fedit -file /etc/motd -op write -textfile new-motd.txt -v

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map — Structural overview of a file

# Map a Go file — see all functions, types, imports
fedit -file main.go -op map -lang go

# Map a Dockerfile — see stages and instructions
fedit -file Dockerfile -op map -lang dockerfile

# Map a Makefile — see variables, targets, duplicates
fedit -file Makefile -op map -lang makefile

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Supported Map Languages (17)

Language	Key Structures Detected
go	package, imports, types, interfaces, functions
python	imports, classes, functions, decorators
javascript	imports, exports, classes, functions, arrows
typescript	(same as javascript)
css	imports, custom properties, selectors, @media, @keyframes
rust	use, mod, struct, enum, trait, impl, fn, macro_rules!
java	package, imports, classes, interfaces, enums, methods
csharp	using, namespace, classes, interfaces, records, properties
html	doctype, head/body, headings, scripts, links, forms, ids
sql	CREATE, ALTER, DROP, INSERT, SELECT, indexes, triggers
yaml	document separators, top-level keys
toml	tables, array tables, top-level keys
markdown	headings, code blocks, links
ruby	requires, modules, classes, methods, attributes
php	namespace, use, classes, interfaces, traits, functions
dockerfile	FROM stages, all instructions
makefile	includes, variables, .PHONY, targets

All mappers detect duplicates and flag them with warnings.

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Flags Reference

Flag	Description
-file PATH	Target file (required)
-op OP	Operation to perform (required)
-line N	Starting line number (1-based)
-end N	Ending line number (for ranges)
-text "s"	Inline text content
-textfile F	Read content from a file
-match "s"	Substring to search for
-nth N	Which occurrence (default 1, -1 = last)
-lang LANG	Language for map operation
-v	Verify: show affected lines after edit

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Real-World Examples

Patch an Nginx config in a deploy script

#!/bin/bash
# Update upstream server and reload

fedit -file /etc/nginx/conf.d/app.conf \
  -op replaceall \
  -match "server 10.0.1.50:8080" \
  -text "server 10.0.1.51:8080" -v

nginx -t && systemctl reload nginx

Add a cron job to crontab

fedit -file /etc/crontab \
  -op insertafter \
  -match "# Custom jobs" \
  -text "0 2 * * * root /opt/backup.sh" -v

Bulk update version in multiple files

for f in Makefile config.yaml package.json; do
  fedit -file "$f" -op replaceall -match "1.1.0" -text "1.2.0" -v
done

Inspect a Dockerfile before editing

fedit -file Dockerfile -op map -lang dockerfile
# See the structure, then surgically edit:
fedit -file Dockerfile -op insertafter -match "FROM alpine" -text "RUN apk add --no-cache curl" -v

Remove a block from a config

# First, find the lines
fedit -file app.conf -op find -match "deprecated-feature"
# Output says lines 44-49, so:
fedit -file app.conf -op delete -line 44 -end 49 -v

PowerShell workflow (Windows sysadmins)

# Set an alias
$f = "C:\tools\fedit.exe"

# Find all TODO comments in Go code
& $f -file main.go -op find -match "TODO"

# Replace a config value
& $f -file config.toml -op replaceall -match 'debug = true' -text 'debug = false' -v

# Map a file to understand its structure
& $f -file main.go -op map -lang go

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Tips

• Always use -v on mutations — it costs nothing and saves you from blind edits
• Use find before replace — get the exact line numbers first
• Prefer insertafter/insertbefore over insert — matching is more resilient than hardcoded line numbers
• Use -nth -1 to target the last occurrence of a match
• Use -textfile for multi-line inserts — avoids shell quoting headaches
• map before editing unfamiliar files — see the structure first

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License

MIT — see LICENSE

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Built by Amalex — makers of Amalex Handler, the universal file transporter.