If your Mac previously "purchased" El Capitan, it may still appear in your App Store history.
hdiutil detach /Volumes/Install\ OS\ X\ El\ Capitan hdiutil convert /tmp/ElCapitan.cdr.dmg -format UTOI -o ~/Desktop/ElCapitan.iso Use code with caution. Mac Os X 10.11 El Capitan Iso Download
Reviewers generally praised the update for making the Mac experience feel "snappier". If your Mac previously "purchased" El Capitan, it
Mac OS X 10.11 El Capitan is a stable and feature-rich operating system. However, if you're looking to download the ISO, be sure to exercise caution and only download from reputable sources. Mac Os X 10.11 El Capitan Iso Download
If you do not have access to a Mac and must download a pre-made ISO from a third-party site (like Archive.org or tech forums), proceed with caution:
“createinstallmedia: command not found”