Linux common Commands--file management (i)

one , cat

1, function : View the contents of the file, from the first line to the last line ( for smaller files )

2 Common parameters:

-N is numbered by the first line, so the output line

- B is similar in function to-n, and it does not number blank lines

-S encounters a blank line that is substituted for a row with more than two consecutive lines of blank line

3 Example

1, use the cat–n command to view the/etc/dhcpd.conf file

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2 use the cat–b command to view the/etc/dhcpd.conf, comparedwith the above, found that less than five elements.

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two , chgrp

1. function: Change the owning group of the file or directory

2, common parameters

The-c effect is similar to the-v parameter, but returns only the part of the change

-v Show instruction execution Process

-R Recursive processing, all files and subdirectories under the specified directory are processed together

3. Example

1, Add a user group with the groupadd command

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use the ll command to view the details of the Dhcpd.log file, and then change its user group with the CHGRP command

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2 . Use the mkdir command to create a directory in/tmp, Create a file in the new directory with the Touch command, and then use the LL command to view the group that the file and directory belongs to

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3, use the chgrp-rv command to change the group that the/TMP/ZJC directory file belongs to.

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use the ll command to see if the/TMP/ZJC directory and the files inside change the owning group

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Four,chmod

1. function: Change the permissions of a file or directory

2 Additional Instructions

U:user, which is the owner of a file or directory

G:group, which is the owning group of the file or directory,

O:Other, except for files or directories owned by or belonging to the group, other users belong to this scope

A:all, that is, all users, including the owner, the group that belongs to other users.

R: Read permission, the number "4 " represents, that is, 2 of the 2- Time Square

W: Write permission, the number "2 " represents, that is, 2 of the 1- Time Square

X: Execute permission, the number "1 " represents, that is, 2 of the 0- Time Square

-: Without any permission, the number "0" represents

3. Common Parameters

-F does not display error messages

-R Recursive processing, processing all files and subdirectories under the specified directory

< permissions >+< permissions Settings > The permission setting for a file or directory that has permission scope enabled

< permissions >-< permissions settings > close permission settings for a file or directory

< permissions >=< permissions Settings > Specify permission scopes for files or directories that have this permission configured

4, example one

1. Create a directorywith mkdir, touch create file, and ll View Details

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2. Add the data.txt file owner to execute permissions, add Write permission to the owning group

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3, close so people Read permission to the Data.txt file, give the owner, the person outside the group has Read permission.

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4. use the chmod–r command to Add the/TMP/LX directory and the owner of the file inside it to execute permissions

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5. example Two

1. Creating directories and Files

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2, use the chmod command to express the relevant permissions with a number, and recursively assign permissions to directories and files in the directory with Chmod–r

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Five,chown

1. function: Change the owner or group of the file or directory

2, common parameters

-H changes the file of the symbolic connection without altering any other related files

-R Recursive processing, so that files and subdirectories under the specified directory are processed together

-v Show instruction execution Process

3. Example

1, Create a user with Useradd, and create directories and files with mkdir,touch

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2, use chown to change the owner of the/tmp/chown/centos, using chown-r for recursive changes /tmp/chown The owning group of the files in the directory and directory

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This article is from the "ZJC" blog, make sure to keep this source http://zjclinux.blog.51cto.com/9796061/1663711

Linux common Commands--file management (i)