You can use Ruby to set the status line in Claude Code

Claude Code's status line can be configured to run a Ruby script, as demonstrated by developer Lucian Ghinda, who shared a setup using a `statusLine` command in `settings.json` to display context window usage, git branch, and current directory. The script reads JSON session data from stdin and outputs a formatted string, with an optional `refreshInterval` for more frequent updates. Ghinda warns that forking git processes can cause timeouts on large repositories.

Claude Code can run executables to show the status line, and, of course, that executable can be a Ruby script. Here is the simple setup to do that: { "statusLine": { "type": "command", "command": "/Users/lucianghinda/.claude/statusline.rb" } } statusLine is a top-level setting and sits on the same level as permissions and hooks . If you want to apply it to all projects, put that configuration in ~/.claude/settings.json . The script that you specify there should be marked as executable with chmod +x , and it should include this at the top of the file: bash /usr/bin/env ruby I have not yet tested whether I can remove that shebang instruction and change the “command” argument to ruby /Users/lucianghinda/.claude/statusline.rb . I would assume it could work but have not yet tested it. The status line behaves like a filter: Claude sends a JSON session data https://code.claude.com/docs/en/statusline full-json-schema to a script that you set up there and expects to get back a string, which will be displayed as the status line. The flow looks like this: There is also an optional refreshInterval that can rerun the command more often if you like. You can find the list of events that will trigger a status line update at How status lines work https://code.claude.com/docs/en/statusline how-status-lines-work . Here is the script that I used that Claude generated for me when asked : python def compact tokens return tokens.to s if tokens < 1 000 return format '%.1fk', tokens / 1 000.0 .sub '.0k', 'k' if tokens < 1 000 000 format '%.2fM', tokens / 1 000 000.0 .sub '.00M', 'M' end def color for percent return RED if percent = 80 return YELLOW if percent = 50 GREEN end def git branch cwd branch = cd {cwd.shellescape} && git -c core.fileMode=false rev-parse --abbrev-ref HEAD 2 /dev/null .strip branch.empty? ? 'no-git' : branch end def context segment window return nil unless window used = window 'total input tokens' .to i size = window 'context window size' .to i percent = window 'used percentage' percent = size.positive? ? used.to f / size 100 .round : 0 if percent.nil? label = "ctx {compact used }/ {compact size }" " {label} {color for percent } {percent}% {RESET} {DIM}" end input = begin JSON.parse $stdin.read rescue StandardError {} end cwd = input.dig 'workspace', 'current dir' || input 'cwd' || Dir.pwd parts = File.basename cwd , git branch cwd parts << context segment input 'context window' puts " {DIM} {parts.compact.join ' | ' } {RESET}" In my case, I want to pay attention only to the context window, and that is the most important piece of information added there. You can test the script by doing something like this: echo '{"workspace":{"current dir":"/Users/lucianghinda/.claude"},"context window":{"total input tokens":123456,"context window size":1000000}}' | ~/.claude/statusline.rb Output should be: .claude | no-git | ctx 123.5k/1M 12% My current script checks git with rev-parse , which forks a process each time it runs. For a normal repository, that should return quickly, but in case of a slow network or a more complex repository with many objects in Git, it can take longer, and Claude will time out on the command and not display anything in the status line.