Skip to content
CRT

Environment Variables Reference

CRT_CONFIG_DIR

Section titled “CRT_CONFIG_DIR”
Attribute Value
Type Absolute path string
Default ~/.config/crt

Overrides the directory CRT uses to locate config.toml, the themes/ subdirectory, and the fonts/ subdirectory. Must be an absolute path. If a relative path is supplied, CRT logs a warning and ignores the variable, falling back to ~/.config/crt.

Example:

Terminal window
CRT_CONFIG_DIR=/opt/myteam/crt-config crt

Use cases:

  • Running multiple CRT configurations side-by-side.
  • Isolating config in CI or test environments.
  • Pointing at a shared or version-controlled config directory.

CRT_PROFILE

Section titled “CRT_PROFILE”
Attribute Value
Type Any value (presence is checked, not the value)
Default Unset (profiling disabled)

Setting this variable to any value enables profiling mode at startup. Profiling collects per-frame timing (total, update, render, present, effects phases), memory samples (RSS, sampled every second), subsystem durations, slow-frame events (>16 ms), and periodic grid snapshots. Output is written to ~/.config/crt/profile-{unix_timestamp}.log.

Setting CRT_PROFILE also changes the default RUST_LOG filter from warn,crt=info to warn,crt=debug,crt_renderer=debug,crt_theme=debug,crt_core=debug, producing verbose logs in the profile file.

Profiling can also be toggled at runtime without a restart via Cmd+Option+P or View > Start Profiling in the menu.

Example:

Terminal window
CRT_PROFILE=1 crt

Use cases:

  • Diagnosing frame rate drops or jank.
  • Measuring effect performance before filing a bug report.
  • Sharing a profile log with developers for analysis.

CRT_BENCHMARK

Section titled “CRT_BENCHMARK”
Attribute Value
Type Any value (presence is checked, not the value)
Default Unset

Enables benchmark mode in the benchmark_gpu binary. Not meaningful when passed to the main crt binary. Referenced in benchmark_gpu usage output.

Example:

Terminal window
CRT_BENCHMARK=1 cargo run --release --bin benchmark_gpu

Use cases:

  • Automated GPU rendering benchmarks in CI.
  • Comparing frame timing across builds or hardware.

RUST_LOG

Section titled “RUST_LOG”
Attribute Value
Type env_logger filter string
Default (normal mode) warn,crt=info
Default (profiling mode) warn,crt=debug,crt_renderer=debug,crt_theme=debug,crt_core=debug

Standard env_logger directive. Controls log verbosity for CRT and its crates. When CRT_PROFILE is set, CRT automatically uses the debug filter unless RUST_LOG is explicitly set, in which case the explicit value takes precedence.

Example values:

Value Effect
warn,crt=info Default: warnings globally, info for CRT crate
warn,crt=debug,crt_renderer=debug,crt_theme=debug,crt_core=debug Verbose debug output across all CRT crates
trace Maximum verbosity for all crates (very noisy)
crt=debug Debug output for the main CRT crate only
error Errors only

Example:

Terminal window
RUST_LOG=crt=debug crt

Use cases:

  • Diagnosing theme loading or config parsing issues.
  • Tracing font fallback behavior.
  • Investigating rendering or GPU initialization problems.

Summary Table

Section titled “Summary Table”
Variable Affects Required
CRT_CONFIG_DIR Config file, themes directory, fonts directory No
CRT_PROFILE Enables profiling, switches to debug log level No
CRT_BENCHMARK Enables benchmark mode in benchmark_gpu binary No
RUST_LOG Log verbosity filter No