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Directory and file operations

Various ways to view files

●Displays the number of files in a directoryThe ls command allows you to view files in the current directory or in a specific directory.It can also tell you the number of files instead of the file or directory name.In such a case, you can get the number of files by using the find command, which is a file search command, together with the wc command, which does the countingUse the find command with the directory you want to count as an option, the file type with the "-type" option, and then use the pipe "|" to count the number of lines with the wc command with the "-l" option to display the number.
2020.09.24
Directory and file operationsLinuxTips(RedHat)_en
Directory and file operations

File comparison

●Compare two filesTo see if there is a difference between the two files, use the "cmp" command.Specify the file you want to compare as an argument and run it.If there is a difference, it will print the byte position and line number. Also, if there is no difference, the cmp command will not display any message, only a prompt.
2020.09.24
Directory and file operationsLinuxTips(RedHat)_en
Directory and file operations

Extraction of strings and lines in a file

●Extract strings that start with a specific characterIf you want to extract a specific string from a long file, use the grep command.By specifying the string to be extracted and the file as the arguments of the grep command, and by adding "^" (carrot) as an additional condition to extract data starting from a specific string, you can extract data starting from that string.
2020.09.24
Directory and file operationsLinuxTips(RedHat)_en
Directory and file operations

File manipulation with tar command

●View the contents of the archive created by the tar commandTo view the contents of an archive created by the tar command, run the tar command with the "t" option.If you have saved the file as a file, use the "f" option together.If the "v" option is not used, only the names of the files included in the archive will be displayed; if it is used, detailed information such as the attributes of each file will be displayed.※The tar command can omit the "-" (hyphen) option specification.
2020.09.24
Directory and file operationsLinuxTips(RedHat)_en
Disk and device management

Check the hard disk usage.

To check the Linux hard disk information, use the "df command".The df command is used to set the hard disk'sUsed spaceFree spacePercentage of usageThe df command displays the following informationIn Linux, hard disks are treated as special files called device files.IDE drives have the names /dev/hda (primary star hard disk), /dev/hdb (primary slave hard disk), etc. on Linux systems.The results of the df command will also show the names of these files, so you can distinguish between them and check their usage even if you are using multiple hard disks.
2020.09.24
Disk and device managementLinuxTips(RedHat)_en
Disk and device management

Display the partition table

Display the partition tableTo view the partition table, run ...
2020.09.24
Disk and device managementLinuxTips(RedHat)_en
Disk and device management

Show the available formatting formats.

Linux supports multiple file formats, and this tends to increase with each version upgrade.So, if you want to check what file formats are supported, you can run the fdisk command with the device as an argument, and then run the interactive command "l" to display the list of supported files.
2020.09.24
Disk and device managementLinuxTips(RedHat)_en
Disk and device management

Inspect the file system.

If a problem is suspected in the file system, use the fsck command to inspect the file system.When the fsck command is executed, it will check the file system for abnormalities, and if any abnormalities are found, it will display a return value depending on the nature of the problem.If no abnormality is found, the number of files contained on the disk, the number of blocks in use, and the number of available blocks will be displayed.If the command is executed with no arguments, all devices described in /etc/fstab will be scanned, and if the command is executed with a device name specified as an argument, only the specified device will be scanned.Caution.Since disk access while the check is in progress may destroy the system, it is safe to unmount any volume that can be unmounted when executing the fsck command, and to run it in single-user mode if it contains a volume on which / is placed.
2020.09.24
Disk and device managementLinuxTips(RedHat)_en
Disk and device management

Check for filesystem consistency.

Use the e2fsck command to check the consistency of the file system for ext2 (Linux 2nd extended file system) and ext3 (Linux 2nd extended file system with journal and automatic record keeping).Specify the device name of the volume to be checked as an argument.Caution.Since disk access while the inspection is in progress may destroy the system, it is safe to unmount any volume that can be unmounted when running the e2fsck command, and to run it in single-user mode if it contains a volume with / placed on it. Also, root privileges are required to run this e2fsck command.
2020.09.24
Disk and device managementLinuxTips(RedHat)_en
Disk and device management

Check the status of the SCSI host adapter.

Check the status of the SCSI host adapter.To find out the manufacturer, model name, model number, and connection status of the SCSI card in a system with a SCSI card installed, you can check the status of the SCSI card by viewing the information in the "/proc/scsi/scsi" file.
2020.09.24
Disk and device managementLinuxTips(RedHat)_en
Disk and device management

Displays information on I/O addresses.

I/O address informationOn Linux systems, you can display the memory map of the CPU reserved for I/O devices.To display the information, refer to the /proc/ioports file.You can use the more or less command to see the screen transition.
2020.09.24
Disk and device managementLinuxTips(RedHat)_en
LinuxTips(RedHat)_en

Reboot the system immediately.

reboot is a command to reboot the system immediately.Usually, the shutdown command is used to stop the system, but reboot is a shortened form of the shutdown command.To reboot the system with the shutdown command, you need to add the option "r" as an argument, but reboot does not need any argument.There is also halt, which is a command to stop the system immediately as well as reboot.
2020.09.24
LinuxTips(RedHat)_ensystems-management
LinuxTips(RedHat)_en

Display various information of memory

Display various information of memory●Information about memoryTo get information about memory, refer to the /proc/meminfo file.This file is used as the memory information displayed by the top, free, and vmstat commands.
2020.09.24
LinuxTips(RedHat)_ensystems-management
LinuxTips(RedHat)_en

Display the status of a process

To view the processes, use the ps command.When the ps command is executed, it will display the process information based on the information under /proc.If the ps command is executed without any options, the process status of the user who executed the command will be displayed.
2020.09.24
LinuxTips(RedHat)_ensystems-management
LinuxTips(RedHat)_en

Show all processes

Show all processesTo see all the processes, run the ps command with the "-a" option.If you want to see the processes executed by the logged-in user, you can use the "-a" option without any arguments, but if you want to see which processes are being executed by other users, you can use the "-u" option as well.
2020.09.24
LinuxTips(RedHat)_ensystems-management
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