This is not a command the end user would want to run . Ever . This documentation is meant for people who are studying the plumbing scripts and/or are writing new ones . gitsh -i18n --envsubst is Git stripped -down copy of the GNU envsubst(1) program that comes with the GNU gettext package . It used internally by git-sh-i18n (1)to interpolate the variables passed to the eval_gettext function . No promises are made about the interface, or that this program won disappear without warning in the next version of Git . Don use it .