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koolba

I do this all the time for particularly scary yet infrequent scripts that I’m paranoid for accidentally executing.

The simpler ones check an environment variable such as RUN_SCARY_THINGY is set to “yes”.

The complex ones check that it has a timestamp that is within the past minute.

Accidentally run the script without exporting the right var and it prints a message suggesting a cup of coffee.

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When writing and running SQL one-offs interactively, I will surround it with `if 1<>1 begin end` or comments, or add syntax errors at the top so that I won't accidentally run it without first selecting the part I want to run. I should get into the habit of writing `begin; rollback` instead for extra-safety.

And I always write the WHERE clause before the DELETE or UPDATE keywords.

> And I always write the WHERE clause before the DELETE or UPDATE keywords.

I sometimes get nervous typing 'rm -r' commands, since it starts with a very broad path, and only narrows-down as we type more, e.g. if we hit enter prematurely when typing 'rm -r ~/Downloads/archive.zip' we might delete our entire home directory, or all of our downloads.

For this reason I often prefix dangerous steps with 'echo'; once I'm confident it's correct, I'll then run the script and double-check that variables/flags/etc. expanded as expected; and only then will I remove the echoes.

When I was still a student, I accidentally erased all my project source code with:

rm * .o

I was puzzled by the message ".o: No such file", and then understood why...

Now, I always start with ls and if satisfied of the output, replace ls with rm

Similarly, i sometimes start writing the command line with 'ls' or 'find', and then run it, and once i'm satisfied it describes the right things, i change the find to an rm.

I always write rm <path> -rf for this reason

(I was surprised to learn that on some systems, the flags are in a fixed position, at the start!)

One reason for having the flags before the <path> is so that you can terminate the flags by using '--'. This is especially useful to prevent dubious files being expanded that might start with '-' and be interpreted as flags that leads to unexpected results.

Note that my Debian's `rm` happily supports terminating flags using `--` when necessary, so wanting to support `--` syntax doesn't have to come at the expense of writing -r last.

Almost always, if I'm inputting `rm` manually in a shell, I don't need `--`; very few filenames on my disk start with -.

Quite a lot of SQL dialects allow the syntax "DELETE * FROM X" for this exact reason, allowing you to more easily change a select statement into a delete.

The above solution unfortunately doesn't work for those of us who use fzf (or other fuzzy runners), since that RUN_SCARY_THINGY=yes var will be part of the matched line which you will run inadvertently in your coffee-deprived mind. I rarely make mistakes while consciously typing out commands, but running commands with wrong arguments because I didn't pay enough attention on the matched line does happen semi-regularly. Doesn't help that since doing stuff with fzf is much faster than typing out full commands, that your brain sometimes just doesn't have enough time to ask -- wait, should I be running this right now?

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