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-releaseCentOS Linux release 7.3.1611 (Core)cat /etc/redhat-releasehttp://mirror.centos.org/centos/7/os/x86_64/Packages/ftp-0.17-67.el7.x86_64.rpmrpm -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 -ltotal 12200788-rw-r--r-- 1 xxxx xxxx 12493601071 Mar 14 18:18 Windows.zipxxxx@ubuntu:/tmp$ ls -lhtotal 12G-rw-r--r-- 1 xxxx xxxx 12G Mar 14 18:18 Windows.zipLinux 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 -h4.0K    ./.X11-unix4.0K    ./.ICE-unix12G     .查看系统磁盘设备，默认是KB为单位：xxxx@ubuntu:/tmp$ dfFilesystem                  1K-blocks     Used Available Use% Mounted on/dev/mapper/ubuntu--vg-root  87845160 24205024  59154812  30% /none                                4        0         4   0% /sys/fs/cgroupudev                          4019860        4   4019856   1% /devtmpfs                          806220      592    805628   1% /runnone                             5120        0      5120   0% /run/locknone                          4031088        0   4031088   0% /run/shmnone                           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 -hFilesystem                   Size  Used Avail Use% Mounted on/dev/mapper/ubuntu--vg-root   84G   24G   57G  30% /none                         4.0K     0  4.0K   0% /sys/fs/cgroupudev                         3.9G  4.0K  3.9G   1% /devtmpfs                        788M  592K  787M   1% /runnone                         5.0M     0  5.0M   0% /run/locknone                         3.9G     0  3.9G   0% /run/shmnone                         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 -aFilesystem                  1K-blocks     Used Available Use% Mounted on/dev/mapper/ubuntu--vg-root  87845160 24205024  59154812  30% /proc                                0        0         0    - /procsysfs                               0        0         0    - /sysnone                                4        0         4   0% /sys/fs/cgroupnone                                0        0         0    - /sys/fs/fuse/connectionsnone                                0        0         0    - /sys/kernel/debugnone                                0        0         0    - /sys/kernel/securityudev                          4019860        4   4019856   1% /devdevpts                              0        0         0    - /dev/ptstmpfs                          806220      592    805628   1% /runnone                             5120        0      5120   0% /run/locknone                          4031088        0   4031088   0% /run/shmnone                           102400        0    102400   0% /run/usernone                                0        0         0    - /sys/fs/pstorecgroup                              0        0         0    - /sys/fs/cgroup/cpusetcgroup                              0        0         0    - /sys/fs/cgroup/cpucgroup                              0        0         0    - /sys/fs/cgroup/cpuacctcgroup                              0        0         0    - /sys/fs/cgroup/memorycgroup                              0        0         0    - /sys/fs/cgroup/devicescgroup                              0        0         0    - /sys/fs/cgroup/freezercgroup                              0        0         0    - /sys/fs/cgroup/blkiocgroup                              0        0         0    - /sys/fs/cgroup/perf_eventcgroup                              0        0         0    - /sys/fs/cgroup/hugetlb/dev/sda1                      240972    37043    191488  17% /bootbinfmt_misc                         0        0         0    - /proc/sys/fs/binfmt_miscsystemd