Recoding unix command ls in c (formatting output)

Question

I'm recoding the Unix command ls, im using multiple system functions including but not limited to , , functions etc. I have all the information I need and have already taken big strides. However, I need help with formatting the output.

when you run the command ls -l and the output is formatted so all columns are the right size regardless of the length of said files names.

I would like to know how to format my output in the same manner as ls, with regard to columns (Just a general idea not actual code). How do I do this?

How would you format it by hand on a piece of paper ? You can also consult the documentation of printf. — Jabberwocky
– Jabberwocky, Commented Jun 9, 2016 at 10:31
Go through this [codingunit.com/…. You'll get a good idea how to do that. — Anand Barnwal
– Anand Barnwal, Commented Jun 9, 2016 at 10:56
In C there are format specifier which can be specified in printf functions. — sameerkn
– sameerkn, Commented Jun 9, 2016 at 10:59
Why are you using the ls command - read up about opendir, readdir etc. and use them instead — Ed Heal
– Ed Heal, Commented Jun 9, 2016 at 12:23

Kenneth Goveas · Accepted Answer · 2016-07-02 07:01:57Z

There are various non-printing escape characters that can perform tasks such as moving the cursor to a specific location, changing the font and background colors, etc. You can use them to move the cursor to calculated positions to achieve the neat column-based formatting like the output of the ls command. The characters you would want to consider are the following:

\033[l;cH: Moves the cursor to line l and column c.
\033[nA: Moves the cursor up n lines.
\033[bB: Moves the cursor down n lines.
\033[nC: Moves the cursor forward n characters.
\033[nD: Moves the cursor backward n characters.
\033[2J: Clears the screen and moves the cursor to line 0 and column 0
\033[K : Without moving the cursor, clear the line starting from the current cursor position.
\033[s : Store the current cursor position
\033[u : Move the cursor back to the previously stored location.

For example, the following statement moves the cursor to the the top-left corner of the screen and clears the first line, and returns the cursor back to its original location.

printf("\033[s\033[0;0H\033[K\033[u");

Collectives™ on Stack Overflow

Recoding unix command ls in c (formatting output)

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related