4 ms·

That over writes though. It doesn't delete. Foofoo\rbar\r Should show as barfoo With the cursor over the start of that line.

dale_glass 3y ago
If there's no newline, cat won't output one, and bash will put the prompt right after: [dale@host ~]$ echo -n "hi" > test [dale@host ~]$ cat test hi[dale@host ~]$ If you add a \r, then the cursor goes back to the start of the line, and the prompt overwrites the "hi". [dale@host ~]$ echo -en "hi\r" > test [dale@host ~]$ cat test [dale@host ~]$
h2odragon 3y ago
depends on the terminal
- jstanley 3y ago
  What terminal interprets "\r" as "clear the line"? I would have thought that is considered a bug.
  - fragmede 3y ago
    most of them do. it's what a /r means. it's how cli programs can easily output a spinning wheel/similar for busy status.
    - jstanley 3y ago
      No, "\r" means return the cursor to the start of the line without clearing the line. Try this: $ echo -ne "ooo\rf\n" foo If a "\r" cleared the line, you would just see a "f", not a "foo".
      - fragmede 3y ago
        isn't that what I said?
    - t-3 3y ago
      You want to know how I know you never wrote your own text editor? Carriage return is a carriage return, not a delete or backspace or clear line.
      - benj111 3y ago
        >Carriage return is a carriage return To be fair it isn't. On typewriters it also adds a new line. On Mac, it is (used to be?) the new line character. I don't know how non vt terminals handled it.
      - fragmede 3y ago
        who said anything about clearing? I just meant that \r goes to the beginning of the line, so you can output a busy spinner
        t-3 3y ago
        > What terminal interprets "\r" as "clear the line"? I would have thought that is considered a bug. >> most of them do. it's what a /r means. it's how cli programs can easily output a spinning wheel/similar for busy status. You did.
    - DonHopkins 3y ago
      You want to know how I know you never wrote your own C program or terminal emulator? /r means "slash, then the letter r". \r means carriage return, which doesn't clear the line, just moves the cursor to the left margin. Unless you're on an Apple ][, in which case CHR$(13) moves to the beginning of the next line, but still doesn't clear anything. And CHR$(4) is where the real magic happens, but it has to follow a CHR$(13)! ]PRINT CHR$(4) + "INIT HELLO"
      - fragmede 3y ago
        you're absolutely right. It's impossible that I've ever written any C, and just fat fingered the / and \. ... Point is, \r goes to the beginning of the line, without going to the next one, as you reiterated, so you can output a spinner using - / - \
dan-robertson 3y ago
Yeah except the file ends in \r so the OP may have had their prompt longer than any of the lines (e.g. [user@hostname cwd] $) such that they couldn’t tell.

dale_glass 3y ago

If there's no newline, cat won't output one, and bash will put the prompt right after: [dale@host ~]$ echo -n "hi" > test [dale@host ~]$ cat test hi[dale@host ~]$ If you add a \r, then the cursor goes back to the start of the line, and the prompt overwrites the "hi". [dale@host ~]$ echo -en "hi\r" > test [dale@host ~]$ cat test [dale@host ~]$

h2odragon 3y ago

depends on the terminal

jstanley 3y ago
What terminal interprets "\r" as "clear the line"? I would have thought that is considered a bug.
- fragmede 3y ago
  most of them do. it's what a /r means. it's how cli programs can easily output a spinning wheel/similar for busy status.
  - jstanley 3y ago
    No, "\r" means return the cursor to the start of the line without clearing the line. Try this: $ echo -ne "ooo\rf\n" foo If a "\r" cleared the line, you would just see a "f", not a "foo".
    - fragmede 3y ago
      isn't that what I said?
  - t-3 3y ago
    You want to know how I know you never wrote your own text editor? Carriage return is a carriage return, not a delete or backspace or clear line.
    - benj111 3y ago
      >Carriage return is a carriage return To be fair it isn't. On typewriters it also adds a new line. On Mac, it is (used to be?) the new line character. I don't know how non vt terminals handled it.
    - fragmede 3y ago
      who said anything about clearing? I just meant that \r goes to the beginning of the line, so you can output a busy spinner
      - t-3 3y ago
        > What terminal interprets "\r" as "clear the line"? I would have thought that is considered a bug. >> most of them do. it's what a /r means. it's how cli programs can easily output a spinning wheel/similar for busy status. You did.
  - DonHopkins 3y ago
    You want to know how I know you never wrote your own C program or terminal emulator? /r means "slash, then the letter r". \r means carriage return, which doesn't clear the line, just moves the cursor to the left margin. Unless you're on an Apple ][, in which case CHR$(13) moves to the beginning of the next line, but still doesn't clear anything. And CHR$(4) is where the real magic happens, but it has to follow a CHR$(13)! ]PRINT CHR$(4) + "INIT HELLO"
    - fragmede 3y ago
      you're absolutely right. It's impossible that I've ever written any C, and just fat fingered the / and \. ... Point is, \r goes to the beginning of the line, without going to the next one, as you reiterated, so you can output a spinner using - / - \

dan-robertson 3y ago

Yeah except the file ends in \r so the OP may have had their prompt longer than any of the lines (e.g. [user@hostname cwd] $) such that they couldn’t tell.