nerd-font

name	nerd-font
description	Use when editing Nerd Font icons, Private Use Area glyphs, terminal prompts, tmux status bars, or CLI UI symbols.

Nerd Font Glyphs

Use this skill when a file contains or generates Nerd Font icons. Preserve exact bytes; do not trust how glyphs look in the editor.

Background

Nerd Fonts patch programming fonts with icons from sets such as Font Awesome, Devicons, and Octicons. Many live in Unicode Private Use Area ranges:

• U+E000 through U+F8FF
• U+F0000 through U+FFFFF

They may render as icons, blanks, or replacement boxes depending on the tool. Visual inspection does not prove they survived an edit.

Safe Editing Rules

• Prefer targeted command-line edits that preserve untouched bytes, such as perl -0pi, sed, or a proven formatter.
• Do not retype invisible glyphs by sight. Insert them from codepoints or byte escapes.
• Before editing a line with glyphs, capture a hex dump. After editing, compare the bytes that should have been preserved.
• Avoid broad rewrites of files containing glyphs unless the rewrite tool is known to preserve Private Use Area characters.

Inserting Glyphs

Use codepoints or UTF-8 byte escapes:

# Print a Font Awesome check glyph by codepoint.
printf '\U0000F00C'

# Convert a codepoint to UTF-8 hex bytes.
printf '\U0000F00C' | xxd -p

# Convert a codepoint to printf-style byte escapes.
codepoint="F00C"
printf "\\U0000${codepoint}" | xxd -p | sed 's/\(..\)/\\x\1/g'

For macOS sed, use -i '':

sed -i '' "s/ICON_CHECK/$(printf '\xef\x80\x8c')/" file.sh

For GNU sed, use -i:

sed -i "s/ICON_CHECK/$(printf '\xef\x80\x8c')/" file.sh

Verifying Glyphs

Hex dump relevant lines before and after the edit:

sed -n '29,31p' file.sh | xxd

For a single expected codepoint:

printf '\U0000F00C' | xxd -p

If the expected bytes are absent after the edit, restore the line from git or reinsert the glyph from the codepoint/byte escape.

Common Glyphs

Name	Nerd Font name	Codepoint	UTF-8 bytes
check	nf-fa-check	U+F00C	ef 80 8c
times	nf-fa-times	U+F00D	ef 80 8d
clock	nf-fa-clock_o	U+F017	ef 80 97
bolt	nf-fa-bolt	U+F0E7	ef 83 a7
git branch	nf-dev-git_branch	U+E725	ee 9c a5
folder	nf-fa-folder	U+F07B	ef 81 bb
file	nf-fa-file	U+F15B	ef 85 9b
warning	nf-fa-warning	U+F071	ef 81 b1
info	nf-fa-info_circle	U+F05A	ef 81 9a
cog	nf-fa-cog	U+F013	ef 80 93
arrow right	nf-fa-arrow_right	U+F061	ef 81 a1
search	nf-fa-search	U+F002	ef 80 82

Use the Nerd Fonts cheat sheet for icons not listed here, then verify the codepoint-to-byte conversion locally before editing tracked config.