The subject is UNIX Based off of Your UNIX/Linux The Ultimate Guide 3 rd edition

Question

The subject is UNIX

Based off of Your UNIX/Linux The Ultimate Guide 3rd edition

Please answer questions and include the Exercise number.

Exercises:

8.9 (i and iii), Frame aliases to show (i) only the hidden filenames in the current directory, (ii) the listing of all symbolic links in the current directory and below, (iii) the absolute pathname of a filename specified as argument to the alias.

8.15, Why do shells use a profile as well as an rc file? What types of entries do you place in each?

8.18, How can you make all of your aliases placed in ~/.alias available in all sub-shells? Will the aliases be available in a shell script in (i) Korn, (ii) Bash?

8.19 Devise a system which allows you to use an alias named current to display recursively only the ordinary files in the current directory tree which have been modified since you logged in.

9.17 Assuming that a user may be logged in more than once, how do you (i) list only those users, (ii) mail root a sorted list of all users currently logged in, where a user is listed only once?

Thank You!                      

Explanation / Answer

8.9 (i) only the hidden filenames in the current directory,

In order to show all the hidden files in an directory we can use linux commands. Those commands are as followed:
- ls -lart : We can use this command to list the hidden files in directory.
- ls -ltr : We can use this command to list the files in directory.

ii) the listing of all symbolic links in the current directory and below,

In order to show all sybolic links in the current directory we can use commands like:
- df -h : It will show all the list of directory in human view and there symbolic links

If you wonna make symbolic link then we can use ln -s directory name

(iii) the absolute pathname of a filename specified as argument to the alias.

In order to list the files in the linux we must use the commands like
- ll: Long list
- ls : short list

We can even find out the absolute pathname of the files and argument to the alias.

8.15, Why do shells use a profile as well as an rc file? What types of entries do you place in each?

We use shells and shells use a profile as well as an rc files because shell are very interactive comparing with the rc files. So in order to get better performances in the users uses we need shells to script the activities and users tasks.

Scripting also better used in shells not in rc files and most of the profiles scripting will done in the shell files like .bash_profile, .bash_login and .profiles.

Note: According to the chegg rules I have answered only one question. For remains answers please post remaining questions in a saperate post. Thank you for your understandings.

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