Ed isn't something you would personally use. It's installed here because it can be used by the patch program if you encounter an ed-based patch file. This happens rarely because diff-based patches are preferred these days. Install Ed by running the following commands: cp buf.c buf.c.backup && sed 's/int u/int u, sfd/' buf.c.backup | \    sed '/.*\*mktemp.*/d' | \    sed 's/.*if (mktemp.*/ sfd = mkstemp(sfn);\    if ((sfd == -1) || (sfp = fopen (sfn, "w+")) == NULL)/' > buf.c && ./configure --prefix=/usr && make && make install && mv /usr/bin/ed /usr/bin/red /bin