Unix命令行程序和内建指令文件系统▪cat▪cd▪chmod▪chown▪chgrp▪cksum▪cmp▪cp▪du▪df▪fsck▪fuser▪ln▪ls▪lsattr▪lsof▪mkdir▪mount▪mv▪pwd▪rm▪rmdir▪split▪touch▪umask