Lesson 17: Modifying Deployed Config Files at Runtime With `sed -i`¶

Files affected: scripts/ocws-state.sh, scripts/ocws-media-widget-updater.sh Severity: High — permanently corrupts widget source files; changes survive reboots

What Happened¶

Several scripts use sed -i to modify widget .widget files in-place at runtime:

# ocws-state.sh — update_media_widgets()
sed -i 's|If(XMediaStatus != "none", "Artist: ".*"No media playing")|...|g' \
    "$player_widget"

sed -i 's|value = If(XArt != "none",.*|value = "/tmp/ocws-cover.jpg"|g' \
    "$media_widget"

# ocws-media-widget-updater.sh
sed -i "s|.*\\(value = \"/tmp/ocws-cover.jpg\"\\).*|...|" "$media_widget"

sed -i '/image {/a\...' "$widget_path"

These sed -i calls rewrite the deployed widget source files every time media state changes. This creates several problems:

Idempotency breaks. After the first run, the sed pattern no longer matches (the file has already been changed), so subsequent runs either silently do nothing or apply the substitution to already-substituted text, producing double-nested expressions.
Git diffs are permanently dirty. Widget files in the repo are modified by runtime state. Every git status shows changes; every git diff is noise.
Reinstallation silently reverts. Running install.sh again overwrites the sed-modified files with the originals — all runtime changes are lost.
No rollback path. There's no record of what the file looked like before the sed ran. sed -i with no backup flag is irreversible.
Race condition. If zigshell-cairo-pango reads the widget file while sed -i is writing it (mid-rewrite), zigshell-cairo-pango sees a partial file.

The Fix¶

Separate config from state. Widget source files should be static templates. Runtime values should be injected via the OCWS Event Bus (ocws-emit), not by rewriting the source file.

# WRONG — modifying the source file
sed -i 's|value = ".*"|value = "/tmp/ocws-cover.jpg"|' "$media_widget"

# RIGHT — emit the value through the event bus
ocws-emit.sh Media.CoverArt "/tmp/ocws-cover.jpg"

The widget reads the live value from the IPC channel:

# media.widget (static, never modified by scripts)
image {
  value = XMediaCoverArt
  interval = 1000
  style = "media_cover"
}

For cover art paths specifically, the daemon already writes to /tmp/ocws-cover.jpg — the widget just needs to reference that fixed path. No sed needed at all.

When `sed -i` Is Acceptable at Runtime¶

sed -i is safe at runtime only when: - The file is generated fresh on every boot/start (not a committed source file). - The edit is idempotent — running it twice produces the same result as running once. - A backup is made: sed -i.bak ... so rollback is possible.

# Acceptable: modifying a generated file, idempotent, with backup
sed -i.bak "s/__THEME__/$theme_name/g" "$generated_config"

The General Rule¶

Source files in the repo must not be modified by runtime scripts. Runtime data belongs in state files (/tmp/, ~/.config/ocws/state/), environment variables, or IPC channels — never in .widget or .config files that are under version control.

What changes	Where it lives
Current volume	`ocws-emit System.Volume 75`
Current song	`ocws-emit Media.Title "Song Name"`
Cover art path	Write to `/tmp/ocws-cover.jpg`; widget references fixed path
Theme colors	Generate CSS from template; never patch the template in-place
Widget layout	Edit the source `.widget` manually; never via `sed -i` at runtime

How to Catch It¶

# Find all sed -i calls targeting dotfiles or widget files
grep -rn 'sed -i' scripts/ --include="*.sh" | grep -v '\.bak\|\.tmp\|generated'

# Check if any widget files have been modified outside of git-tracked changes
git diff --name-only dotfiles/ocws/*.widget

Lesson 17: Modifying Deployed Config Files at Runtime With sed -i¶