Chanjin yanayi shine ƙimar mai suna mai ƙarfin gaske wanda zai iya shafar yadda hanyoyin tafiyar zasuyi aiki akan kwamfuta. Suna daga cikin muhallin da tsari yake gudana. Misali, tsari mai gudana na iya neman kimar canjin yanayin TEMP don gano wurin da ya dace don adana fayilolin wucin gadi, ko HOME ko USERPROFILE mai canji don nemo tsarin kundin adireshin mallakar mai amfani da ke aiwatar da aikin. A cikin dukkan tsarin Unix da Unix, da kuma akan Windows, kowane tsari yana da nasa tsarin daban na masu canjin yanayi. Ta hanyar tsoho, lokacin da aka kirkiro wani tsari, yana gadar da wani yanayi mai gudana na tsarin aikin iyayensa, banda bayyanannun canje-canje da iyaye suka yi lokacin da suka kirkiro yaron. A matakin API, dole ne a aiwatar da waɗannan canje-canjen tsakanin fork da exec. Robbins, Arnold; Beebe, Nelson H. F. (May 2005). Apandi, Tatiana; Randal, Allison; Witwer, Adam (eds.). Classic Shell Scripting (1 ed.). O'Reilly. ISBN 978-0-596-00595-5. The Single UNIX Specification - The Open Group Base Specifications, IEEE Std 1003.1-2008 (Issue 7 ed.).