当一个用户没有某些挂载目录的读权限时，使用 df -h 命令会不显示这些目录。但是如果给 df 命令加上 –all 选项，则又可以看到这些目录。例如：
$ df --all
Filesystem 1K-blocks Used Available Use% Mounted on
...
/dev/mapper/share2 - - - - /test/02
/dev/mapper/share1 - - - - /test/01Read-only file system# mount -o remount rw /run（补充：这里以重新挂载 /run 目录并给此目录添加读和写权限为例）
非正常关机可能造成文件系统受损，系统重启后，受损的分区自动挂载后就会变成只读。此时修复这个分区则可能修复这个问题
# fsck.ext4 -y /dev/sda1（补充：这里以修复分区格式为 ext4 的分区 /dev/sda1 为例）
# gzip <option> <file>1) -c or –stdout, write on standard output, keep original files unchanged
2) -d or –decompress, decompress
3) -f or –force, force overwrite of output file and compress links
4) -h or –help, give this help
5) -k or –keep, keep (don’t delete) input files
6) -l or –list, list compressed file contents
7) -n or –no-name, do not save or restore the original name and timestamp
8) -N or –name, save or restore the original name and timestamp
9) -q or –quiet, suppress all warnings
10) -r or –recursive or –rsyncable, operate recursively on directories
11) -t or –test, test compressed file integrity
12) -1 or –fast, compress faster
13) -9 or –best, compress better
# gzip test.txt（补充：这里以压缩文件 test.txt 为例）
# gzip -d test.txt.xz（补充：这里以解压文件 test.txt.zx 为例）
# gunzip <option> <file>1) -c or –stdout, write on standard output, keep original files unchanged
2) -d or –decompress, decompress
3) -f or –force, force overwrite of output file and compress links
4) -h or –help, give this help
5) -k or –keep, keep (don’t delete) input files
6) -l or –list, list compressed file contents
7) -n or –no-name, do not save or restore the original name and timestamp
8) -N or –name, save or restore the original name and timestamp
9) -q or –quiet, suppress all warnings
10) -r or –recursive or –rsyncable, operate recursively on directories
11) -t or –test, test compressed file integrity
12) -1 or –fast, compress faster
13) -9 or –best, compress better
# gunzip test.txt（补充：这里以压缩文件 test.txt 为例）
# gunzip -d test.txt.xz（补充：这里以解压文件 test.txt.zx 为例）
# zip -r eternalcenter.com.zip eternalcenter.directory(Add: Take compressing the eternalcenter.directory directory as an example here)
# zip eternalcenter.com.zip eternalcenter.file(Add: Take compressing the eternalcenter.file file as an example here)