Best 3 from the impressions of reading a new shell programming textbook

I bought it at the end of last year Read on the commuter train in the morning I finally read it after about 3 months

That aside

I read a book called a new shell programming textbook

I would like to write that impression here It may be since junior high school students that the impressions are not good

• It might have been interesting to write my favorite sentence best 3 even when I was in junior high school *

I was a junior high school student at that time

--On your computer --On the Internet --In Markdown notation ――Impressions of programming

You wouldn't even think of writing After all, my dream for the future was to be a cartoonist.

A rough impression of shell programming

** Recommended for beginners to intermediates ** Even though I'm a beginner, I learned a language when I was a student I went to some school for several years, A person like me who doesn't have that kind of thing at all For less than half a year, studying and teaching in a state close to self-study, Beginners after practicing I heard that you are a beginner among engineers When I read it again, it was like this, uh, this was it. It's easy to understand You can review the first half like that, and from the second half you can show off high-level scripts. It is delicious twice

Also, not all command lists are on board. There are also some commands you will use when writing scripts It was just right

Since there is also sample data, after reading It would be nice to be able to download and review

On a desk called Linux
Put a note called bash
With a pen called ShellScript
Write a list of things you want to do
Is it something like

I thought there was such a {command, how to write} best 3!

3rd place : (colon) Parameter expansion

As expected, I can't put the contents of the book [here](http://komaken.me/blog/2014/07/21/bash%E3%81%AE%E6%8B%AC%E5%BC%A7 % E3% 82% 84% E3% 82% B3% E3% 83% AD% E3% 83% B3% E3% 81% AB% E3% 81% A4% E3% 81% 84% E3% 81% A6 /) Is it easy to understand the organized information?

I was surprised that something works just with this : Until now, I used to use it for word division, There is also such a usage It also works as a : (null command)-a command that does nothing called null command.

2nd place ʻuntil` while condition reversal version

As expected, the contents of the book cannot be put on it, and the information in here is easy to understand.

The reverse version is cool, isn't it? ! There is something unexpectedly reversed The repeat condition must be" false " This area also tickles Chunibyo Antilles and sounds are also cool, aren't they?

1st place shift command Shift the argument by one

I wondered if the contents of the book could not be put on it and the information in here was easy to understand.

Where is it used? But I think it's quite convenient to use it I remember reading the contents of this command and the commuter train was shortened. It's fun to think about how to use it and how best to use it

Please comment if you have such a usage.

What I thought I could make such a function Best 3!

3rd place Determine the file format and expand the compressed file

Try reading this book

I thought it would be convenient to make this and make it my own app I wonder if free software works with this kind of mechanism. It seems that I was able to recognize the mechanism of the software that I used casually until now.

2nd place Search for strings from multiple files

Try reading this book

You use it quite often, right? I want to extract the file of this day, or the file of this time Files with larger capacity I'm searching for more options with grep and find It's nice to be able to combine those areas into one script, isn't it?

1st place Handling the trash can on the command line

Please read this as well

I see! It is the content that I thought The scariest thing about working with Linux is If you make a mistake and type a command such as rm or mv It means that the target file disappears very easily, right?

• Of course there is an option to display info * I wondered why there was no such thing as a trash can. This is a script I want to make myself

Next time, let's meet with the best 3 from the impressions of reviewing the new shell programming textbook!