To copy all files having the string "chap" and any two characters after that to the "progs" directory, the correct command is:

A. cp chap?? progs

Explanation: Option A) cp chap?? progs - This option is correct because the command "cp chap??" will copy all files that have the string "chap" followed by any two characters. The copied files will be placed in the "progs" directory.

Option B) cp chap* progs - This option is incorrect because the "*" wildcard symbol matches any number of characters, not just two characters. Therefore, it will copy all files that have the string "chap" followed by any number of characters, not specifically two characters.

Option C) cp chap[12] /progs/. - This option is incorrect because the "[12]" wildcard specifies that either the character "1" or "2" should be present at that position. It does not specify any two characters. Additionally, the "/progs/." path is not needed as the "progs" directory is already specified in the command.

Option D) cp chap?? /progs/* - This option is incorrect because the "/progs/*" path is not needed as the "progs" directory is already specified in the command. Additionally, the "?" wildcard matches any single character, not specifically two characters.

The correct answer is A) cp chap?? progs. This option is correct because it uses the correct wildcard symbol "?" to specify any two characters after the string "chap" and copies the files to the "progs" directory.

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• Wrong explanation

To answer this question, we need to understand the chmod command and its options.

The chmod command is used to change the permissions of a file or directory. The permissions include read, write, and execute permissions for the owner, group, and others.

In this question, we want to remove the read permission for both the group and others from the file 'note'.

Let's go through each option to determine the correct command:

Option A) chmod go r note - This option sets the read permission for both the group and others. It does not remove the read permission. Therefore, this option is incorrect.

Option B) chmod go rw note - This option sets both the read and write permissions for both the group and others. It does not remove the read permission. Therefore, this option is incorrect.

Option C) chmod go-x note - This option removes the execute permission for both the group and others from the file 'note'. It does not remove the read permission. Therefore, this option is incorrect.

Option D) chmod go-r, 4-x note - This option removes the read permission for both the group and others from the file 'note'. It uses the symbolic mode of the chmod command. The 'go-r' part removes the read permission, and the '4-x' part is invalid syntax. Therefore, this option is incorrect.

The correct answer is A. chmod go r note. This option is correct because it removes the read permission for both the group and others from the file 'note'.

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• Wrong explanation