You can customize the behavior of targets with special environment variables. The sections in this help file describe each environment variable, and the tar_envvars() function lists their current values.

tar_envvars(unset = "")



Character of length 1, value to return for any environment variable that is not set.


A data frame with one row per environment variable and columns with the name and current value of each. An unset environment variable will have a value of "" by default. (Customize with the unset argument).


If you modify environment variables, please set them in project-level .Renviron file so you do not lose your configuration when you restart your R session. Modify the project-level .Renviron file with usethis::edit_r_environ(scope = "project"). Restart your R session after you are done editing.


The TAR_ASK environment variable accepts values "true" and "false". If TAR_ASK is not set, or if it is set to "true", then targets asks permission in a menu before overwriting certain files, such as the target script file (default: _targets.R) in tar_script(). If TAR_ASK is "false", then targets overwrites the old files with the new ones without asking. Once you are comfortable with tar_script(), tar_github_actions(), and similar functions, you can safely set TAR_ASK to "false" in either a project-level or user-level .Renviron file.


The TAR_CONFIG environment variable controls the file path to the optional YAML configuration file with project settings. See the help file of tar_config_set() for details.


The TAR_PROJECT environment variable sets the name of project to set and get settings when working with the YAML configuration file. See the help file of tar_config_set() for details.


The TAR_WARN environment variable accepts values "true" and "false". If TAR_WARN is not set, or if it is set to "true", then targets throws warnings in certain edge cases, such as target/global name conflicts and dangerous use of devtools::load_all(). If TAR_WARN is "false", then targets does not throw warnings in these cases. These warnings can detect potentially serious issues with your pipeline, so please do not set TAR_WARN unless your use case absolutely requires it.

See also


#> # A tibble: 3 × 2 #> name value #> <chr> <chr> #> 1 TAR_ASK "" #> 2 TAR_CONFIG "" #> 3 TAR_WARN ""