此文档用于记录自己遇到的问题和解决办法！
1、CentOS执行ftp命令提示ftp:command not found解决方法
centos7.3.1611 安装ftp 客户端工具
[root@xxxx ~]# cat /etc/redhat-release CentOS Linux release 7.3.1611 (Core) cat /etc/redhat-release http://mirror.centos.org/centos/7/os/x86_64/Packages/ftp-0.17-67.el7.x86_64.rpm rpm -Uvh http://mirror.centos.org/centos/7/os/x86_64/Packages/ftp-0.17-67.el7.x86_64.rpm
2、df -h du -h ls -h 命令
xxxx@ubuntu:/tmp$ ls -l total 12200788 -rw-r--r-- 1 xxxx xxxx 12493601071 Mar 14 18:18 Windows.zip xxxx@ubuntu:/tmp$ ls -lh total 12G -rw-r--r-- 1 xxxx xxxx 12G Mar 14 18:18 Windows.zip Linux du命令用于显示目录或文件的大小。du会显示指定的目录或文件所占用的磁盘空间。 xxxx@ubuntu:/tmp$ du -h 4.0K ./.X11-unix 4.0K ./.ICE-unix 12G . 查看系统磁盘设备，默认是KB为单位： xxxx@ubuntu:/tmp$ df Filesystem 1K-blocks Used Available Use% Mounted on /dev/mapper/ubuntu--vg-root 87845160 24205024 59154812 30% / none 4 0 4 0% /sys/fs/cgroup udev 4019860 4 4019856 1% /dev tmpfs 806220 592 805628 1% /run none 5120 0 5120 0% /run/lock none 4031088 0 4031088 0% /run/shm none 102400 0 102400 0% /run/user /dev/sda1 240972 37043 191488 17% /boot 使用-h选项以KB以上的单位来显示，可读性高： xxxx@ubuntu:/tmp$ df -h Filesystem Size Used Avail Use% Mounted on /dev/mapper/ubuntu--vg-root 84G 24G 57G 30% / none 4.0K 0 4.0K 0% /sys/fs/cgroup udev 3.9G 4.0K 3.9G 1% /dev tmpfs 788M 592K 787M 1% /run none 5.0M 0 5.0M 0% /run/lock none 3.9G 0 3.9G 0% /run/shm none 100M 0 100M 0% /run/user /dev/sda1 236M 37M 187M 17% /boot 查看全部文件系统： xxxx@ubuntu:/tmp$ df -a Filesystem 1K-blocks Used Available Use% Mounted on /dev/mapper/ubuntu--vg-root 87845160 24205024 59154812 30% / proc 0 0 0 - /proc sysfs 0 0 0 - /sys none 4 0 4 0% /sys/fs/cgroup none 0 0 0 - /sys/fs/fuse/connections none 0 0 0 - /sys/kernel/debug none 0 0 0 - /sys/kernel/security udev 4019860 4 4019856 1% /dev devpts 0 0 0 - /dev/pts tmpfs 806220 592 805628 1% /run none 5120 0 5120 0% /run/lock none 4031088 0 4031088 0% /run/shm none 102400 0 102400 0% /run/user none 0 0 0 - /sys/fs/pstore cgroup 0 0 0 - /sys/fs/cgroup/cpuset cgroup 0 0 0 - /sys/fs/cgroup/cpu cgroup 0 0 0 - /sys/fs/cgroup/cpuacct cgroup 0 0 0 - /sys/fs/cgroup/memory cgroup 0 0 0 - /sys/fs/cgroup/devices cgroup 0 0 0 - /sys/fs/cgroup/freezer cgroup 0 0 0 - /sys/fs/cgroup/blkio cgroup 0 0 0 - /sys/fs/cgroup/perf_event cgroup 0 0 0 - /sys/fs/cgroup/hugetlb /dev/sda1 240972 37043 191488 17% /boot binfmt_misc 0 0 0 - /proc/sys/fs/binfmt_misc systemd
