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7 . 29 Jobs

1. the difference between soft and hard links

difference: Hard chain Connect refers to a connection made through an index node. In a Linux file system, files saved in a disk partition are assigned a number, called an index node number, regardless of the type. Hard link It cannot span devices, cross partitions. The number of links is incremented after creation, and each directory references the same inode number.

In the delete hard link is, as long as there is a link number, the file exists, the number of links is zero, the file is deleted.

Soft Links The file is a bit like a shortcut to Windows, and when the source file is deleted, the link fails. It can span partitions and can be used for directory

A soft link is another file, the function can be understood as a pointer, action on this file operation in addition to the deletion are directly to the actual point of the file, because it is a real file, so occupy disk space , the content of a symbolic link is the name of the file it refers to. It points to the path of another file whose size is the length of the path string pointed to, and does not increase or decrease The reference count of the target file inode.

2. Convert the contents of the /etc/issue file to uppercase and save to the /tmp/issue.out file

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3. Convert the current system login user's information to uppercase and save to /tmp/who.out

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4. a Linux user sends an email to root asking for the message titled "Help" with the following message body: Holle

, I am username , the system version is Here,please help me to check it, thanks!

Operating system Version Information

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5. /root/ The list of files, displaying them as a line, separated by a space between the filenames

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The contents of the 6.file1 file are: "1 2 3 4 5 6 7 8 9" Calculates the sum of all the numbers

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7. handle the string "xt.,l 1 jr#! $mn 2 c*/fe3 uz4", preserving only the numbers and spaces

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8. Display the PATH variable in a separate row for each directory

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9. Delete blank lines for the specified file

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to display each word (letter) in a file in a separate line, with no blank lines

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One by one. Create user Gentoo, additional group bin and root, default shell For /bin/csh, the annotated message is "Gentoo distribution"

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Create the following user, group, and group memberships

Group with the name admins

User Natasha, using admins as a subordinate group

Harry, also use admins as a subordinate group

User Sarah, not an interactive login system, and not A member ofadmins,Natasha,Harry . ,Sarah 's code is all CentOS .

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This article from "11890466" blog, declined reprint!

7.29 Jobs