Read a tar archive created by gitarchive from the standard input and extract the commit ID stored in it . It reads only the first 1024 bytes of input, thus its runtime is not influenced by the size of the tar archive very much . If no commit ID is found, gitget -tar -commit -id quietly exists with a return code of 1 . This can happen if the archive had not been created using gitarchive or if the first parameter of gitarchive had been a tree ID instead of a commit ID or tag .