Front end developers must read! Starting from scratch, teach you to build a low code website platform in stages>>> 
“can’t create transaction lock on /var/lib/rpm/__ “DB. 000” error resolution
When installing a software through the terminal, it always prompts “can’t create transaction lock on/var/lib/RPM”/__ All along, I thought it was a software problem. After downloading many software versions, they were all wrong. Later, I thought it was a system problem. After looking for it for a long time, I finally knew the reason.
It’s not because of other problems. It’s just that when you install the software yourself, you don’t install the software as root, that is, you don’t have enough permissions. As long as you enter “Su” and password in the terminal and log in as root, you won’t be prompted
It’s too late.
So here to remind you to pay attention to the problem of permissions when installing software
CentOS CDROM mount is still commonly used, so I studied the CentOS CDROM mount, and I’ll share it with you here. I hope the CentOS CDROM mount is useful to you. Using mount command to mount CentOS CDROM, the purpose of learning is to access the data in the mount of CentOS CDROM.
Linux shows that all directories are in a directory tree, regardless of which drive/hardware they are in. In Linux, the disk contents appear as subdirectories. The contents of removable media will not automatically appear in these self directories. We must mount the drive to achieve this.
Mount CentOS CDROM with Mount command
Command: Mount – t auto/dev/CDROM/MNT/CDROM this command is to mount the CentOS CDROM in the/MNT/CDROM directory, where I can access the contents. Learning operation process: [OK]_ 008@CentOS4 ~]$mount – t auto/dev/CDROM/MNT/cdrommount: only root can do that[ OK_ 008@CentOS4 ~]$– switch user operation:[ root@CentOS4 /]#Mount – t auto/dev/CDROM/MNT/cdrommount: the mount point/MNT/CDROM does not exist –/MNT/CDROM directory does not exist and needs to be created first[ root@CentOS4 /]# cd /mnt-bash: cd: /mnt: No such file or directory[ root@CentOS4 /]# [ root@CentOS4 /]#MKDIR – P/MNT/CDROM — create the/MNT/CDROM directory[ root@CentOS4 /]# lsbin dev home lib media mnt proc sbin srv tmp varboot etc initrd lost+found misc opt root selinux sys usr
[ root@CentOS4 /]#Mount – t auto/dev/CDROM/MNT/CDROM — mount CentOS CDROM mount: block device/dev/CDROM is write protected, mounting read only — mount successfully.
[ root@CentOS4 /]#LS – L/MNT/CDROM
dr-xr-xr-x 4 root root 2048 Sep 4 2005 CentOS
-r–r–r– 2 root root 8859 Mar 19 2005 centosdocs-man.css
-r–r–r– 9 root root 18009 Mar 1 2005 GPL
dr-xr-xr-x 2 root root 241664 May 7 02:32 headers
dr-xr-xr-x 4 root root 2048 May 7 02:23 images
dr-xr-xr-x 2 root root 4096 May 7 02:23 isolinux
dr-xr-xr-x 2 root root 18432 May 2 18:50 NOTES
-r–r–r– 2 root root 5443 May 7 01:49 RELEASE-NOTES-en.html
dr-xr-xr-x 2 root root 2048 May 7 02:34 repodata
-r–r–r– 9 root root 1795 Mar 1 2005 RPM-GPG-KEY
-r–r–r– 2 root root 1795 Mar 1 2005 RPM-GPG-KEY-centos4
-r–r–r– 1 root root 571730 May 7 01:39 yumgroups.xml
[ root@CentOS4 /]# [ root@CentOS4 /]#Umount/MNT/CDROM — it’s easy to unload the Centros CDROM mount. You can use umount/MNT/CDROM directly. In addition, other parameters of the mount command can be described as follows: Name: Mount permission: system administrator or users allowed in/etc/fstab: Mount [- HV] mount – a [- ffnrsvw] [- t vfstype] mount [- fnrsvw] [- O options [,…]] device | dir mount [- fnrsvw] [- t vfstype] [- O options] device dir
Note: the content of a file is interpreted as a file system, and then it is hung on a location in the directory. After the command is executed successfully, until we remove the file system with umount, all files under the command will not be called temporarily. This command can be used to mount any file system. You can even use the – O loop option to mount a general file as a hard disk drive. This function is very useful for the interpretation of ramdisk, romdisk or ISO 9660 image files.
Parameters
– V displays program version – H displays auxiliary messages – V displays larger messages, and – F is usually used for debugging- A hang up all the file systems defined in/etc/fstab- The f command is usually used with – A, which generates a run for each mount action. When the system needs to mount a large number of NFS file systems, the mount action can be accelerated- F is usually used for debugging purposes. It makes mount not perform the actual hang up action, but simulate the whole hang up process. Usually used with – V- N generally speaking, mount will write a data in/etc/mtab after it is hung. But when there is no writable file system in the system, you can use this option to cancel this action.
– S-R is equal to – O ro – W is equal to – O RW – L- U hang up the file system with the serial number of the file division- L and – u are meaningful only when files like/proc/partition exist- T specifies the type of the file system, which is usually not required. Mount will automatically select the correct type- O async opens asynchronous mode, and all file reading and writing operations will be performed in asynchronous mode- O sync is executed in synchronous mode- O atime – O noaatime when atime is opened, the system will update the “last call time” of the file every time the file is read.
When we use the flash file system, we may turn this option off to reduce the number of writes.
– O auto – O noauto turns on/off auto hook mode- O defaults use the default options RW, suid, dev, exec, auto, nouser, and async
– O dev – O nodev – O exec – O noexec allows executable files to be executed.
– O suid – O nosuid allows executable files to be executed under root privileges.
– O user – O nouser users can perform mount/umount actions.
– O remount a suspended file system in a different way. For example, the original read-only system is now re hung in read-write mode.
– O RO in read only mode.
– O RW is hung in read-write mode.
– O loop = use the loop mode to partition a file as a hard disk and attach it to the system.
The example hangs/dev/hda1 under/MNT# Mount/dev/hda1/MNT hang/dev/hda1 under/MNT in read-only mode# Mount – O Ro/dev/hda1/MNT hang the image file of/TMP/image.iso under/MNT/CDROM in loop mode. With this method, you can view the contents of the ISO files of Linux CD-ROM which can be found on the general network without burning them to CD-ROM# Mount – O loop/TMP/image.iso/mnt/cdrom related commands umount.
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