3 ms·

I strongly recommend against putting a ">" in your prompt on Unix if you're using any kind of system that supports copy and paste. (So, like, on a physical VT1

by kragen 1y ago

I strongly recommend against putting a ">" in your prompt on Unix if you're using any kind of system that supports copy and paste. (So, like, on a physical VT100 on a serial port it would be okay.) Sooner or later you're going to take a prompt-included command like > ls GN* and accidentally paste it into a terminal window (or a web page that someone else pastes into a terminal window) and accidentally create an empty file named "ls". Or, in some cases, overwrite an existing file. My own current setting is PS1=': ${env:+($env) }\W; ' Which looks like this: : ~; cd wak : wak; ls LICENSE monosrc scripts toybox toybox_awk_test Makefile README.md src toybox_awk_parts : wak; The :; has the advantage that, if you unintentionally include the prompt in your copy and paste, it usually has no effect. (Maybe I should change ($env) to [$env].) \W (the last segment of the directory name) is usually about the right amount of context for me, but if I were working on a project with a lot of directories named things like "views" I would probably reconsider that. BTW, since this prompt collection was written, Linux terminal emulators have mostly gained 24-bit color support, which potentially opens up more alternative colors. See http://canonical.org/~kragen/sw/dev3/gradient.c http://canonical.org/~kragen/sw/dev3/gradient.c with sample results in http://canonical.org/~kragen/sw/dev3/gradient.png http://canonical.org/~kragen/sw/dev3/gradient.png. The escape sequence is \033[38;2;rrr;ggg;bbbm, where \033 is ESC and rrr, ggg, and bbb are decimal numbers from 0 to 255. (Probably I should switch from bash to zsh...)

oneshtein 1y ago
I use Linux for 30 years. Never had this problem. However, I saw newbies, which copy paste commands from tutorials to shell and then frustrated, because # is a comment.
- kragen 1y ago
  I bet you've never accidentally rm -rf'ed your home directory or your email archives either.
  - AdieuToLogic 1y ago
    > I bet you've never accidentally rm -rf'ed your home directory or your email archives either. If this is a concern to mitigate, consider adding the following alias to your preferred shell profile: alias rm='/bin/rm -I' This will not conflict with scripts using PATH-relative 'rm' invocations, yet will provide the desired protection from erroneous interactive use of "rm -rf". See here[0] for details regarding the '-I' flag. 0 - https://linux.die.net/man/1/rm https://linux.die.net/man/1/rm
    - porridgeraisin 1y ago
      I alias rm='rm -i', and then check that I'm deleting the right thing. And then redo the command with `yes | rm -r whatever`. This ends up giving me an "audit log" of what was deleted.
    - kragen 1y ago
      This would have helped when I `rm -rf`ed my home directory, but I was on Ultrix, whose `rm` didn't have the `-I` flag. In fact, I don't think even GNU `rm` had `-I` yet. I was in /tmp/something where I'd unpacked some software package I'd downloaded and decided was of no use, and I wanted to read netnews, so I typed rm -rf * & cd; trn Several hours later, around 3 AM, I was done reading netnews, so I exited trn. Then I remembered that there was one newsgroup I had forgotten to read, so I typed ↑↵ to run trn again, which had the effect of again running rm -rf * & cd; trn but this time in my home directory. And of course my frantic ^C^C^C had no effect on the `rm`, which was safely in the background. Fortunately the computer center kept nightly backups.
  - nailer 1y ago
    I do rm /dir Then go back and add the -rf. Works on GNU and BSD. On GNU only you can ‘rm /dir -rf’
chickensong 1y ago
You can avoid this by using Unicode character U+276F "Heavy Right-Pointing Angle Quotation Mark Ornament", which also looks better IMHO.
AdieuToLogic 1y ago
> I strongly recommend against putting a ">" in your prompt on Unix ... Another reason against using ">" in the definition of PS1 is that this is a typical character used in the definition of PS2[0]. > The :; has the advantage that, if you unintentionally include the prompt in your copy and paste, it usually has no effect. This is because colon (':') has a specific definition in POSIX shells[1], which is: Do nothing beyond expanding arguments and performing redirections. The return status is zero. Note that "performing redirections" can result in destructive file operations. 0 - https://unix.stackexchange.com/questions/193659/in-which-situations-are-ps2-ps3-ps4-used-as-the-prompt https://unix.stackexchange.com/questions/193659/in-which-sit... 1 - https://www.gnu.org/software/bash/manual/html_node/Bourne-Shell-Builtins.html https://www.gnu.org/software/bash/manual/html_node/Bourne-Sh...
- kragen 1y ago
  Right, I shouldn't assume that everyone knows what the `:` command does. I'm not especially worried about destructive file operations in this context because I don't think any of my directories has a `>` in its filename.

by kragen 1y ago

oneshtein 1y ago

I use Linux for 30 years. Never had this problem. However, I saw newbies, which copy paste commands from tutorials to shell and then frustrated, because # is a comment.

kragen 1y ago
I bet you've never accidentally rm -rf'ed your home directory or your email archives either.
- AdieuToLogic 1y ago
  > I bet you've never accidentally rm -rf'ed your home directory or your email archives either. If this is a concern to mitigate, consider adding the following alias to your preferred shell profile: alias rm='/bin/rm -I' This will not conflict with scripts using PATH-relative 'rm' invocations, yet will provide the desired protection from erroneous interactive use of "rm -rf". See here[0] for details regarding the '-I' flag. 0 - https://linux.die.net/man/1/rm https://linux.die.net/man/1/rm
  - porridgeraisin 1y ago
    I alias rm='rm -i', and then check that I'm deleting the right thing. And then redo the command with `yes | rm -r whatever`. This ends up giving me an "audit log" of what was deleted.
  - kragen 1y ago
    This would have helped when I `rm -rf`ed my home directory, but I was on Ultrix, whose `rm` didn't have the `-I` flag. In fact, I don't think even GNU `rm` had `-I` yet. I was in /tmp/something where I'd unpacked some software package I'd downloaded and decided was of no use, and I wanted to read netnews, so I typed rm -rf * & cd; trn Several hours later, around 3 AM, I was done reading netnews, so I exited trn. Then I remembered that there was one newsgroup I had forgotten to read, so I typed ↑↵ to run trn again, which had the effect of again running rm -rf * & cd; trn but this time in my home directory. And of course my frantic ^C^C^C had no effect on the `rm`, which was safely in the background. Fortunately the computer center kept nightly backups.
- nailer 1y ago
  I do rm /dir Then go back and add the -rf. Works on GNU and BSD. On GNU only you can ‘rm /dir -rf’

chickensong 1y ago

You can avoid this by using Unicode character U+276F "Heavy Right-Pointing Angle Quotation Mark Ornament", which also looks better IMHO.

AdieuToLogic 1y ago

> I strongly recommend against putting a ">" in your prompt on Unix ... Another reason against using ">" in the definition of PS1 is that this is a typical character used in the definition of PS2[0]. > The :; has the advantage that, if you unintentionally include the prompt in your copy and paste, it usually has no effect. This is because colon (':') has a specific definition in POSIX shells[1], which is: Do nothing beyond expanding arguments and performing redirections. The return status is zero. Note that "performing redirections" can result in destructive file operations. 0 - https://unix.stackexchange.com/questions/193659/in-which-situations-are-ps2-ps3-ps4-used-as-the-prompt https://unix.stackexchange.com/questions/193659/in-which-sit... 1 - https://www.gnu.org/software/bash/manual/html_node/Bourne-Shell-Builtins.html https://www.gnu.org/software/bash/manual/html_node/Bourne-Sh...

kragen 1y ago
Right, I shouldn't assume that everyone knows what the `:` command does. I'm not especially worried about destructive file operations in this context because I don't think any of my directories has a `>` in its filename.