Yes, though I prefer: echo ...

The reason is that you'll see expanded variables and wildcards before commiting to them.

But prefixing with echo only disables the first command in a pipeline, while commenting it disables the whole thing.

It also executes command and process substitutions, opens files etc. But granted, it's a useful trick in some cases, after passing the fat-fingering stage.

You can move the echo to the part you are currently working on.

It's a pity you can't do something similar to SQL: when writing UPDATE/DELETE always write the WHERE clause first

Something I learned early on when writing possible dangerous SQL selects:

  CREATE TABLE mytable_backup AS SELECT * FROM mytable;
  SELECT * FROM mytable WHERE condition;
  DELETE FROM mytable WHERE condition;

Or just let the DB work for you with BEGIN; + (select/update/delete) + COMMIT; or ROLLBACK;

What I like about SQL is that it's got the double safety of ";". To accidentally run a SQL statement before it's ready in a command line, you'd have to both add the ";" AND hit Enter, or have the bad practice of adding ";" before the statement is ready, or use a bad SQL command line that sees the ";" as optional.

I always start a session with BEGIN, write UPDATEs/DELETEs as SELECTs first and (if possible) use a staging database until I'm fine with the result.

In SQL, you can at least wrap the whole thing in a transaction. Then, just roll the whole thing back if anything came out wrong.

I usually SELECT COUNT(*) WHERE ..., and only subsequently overwrite with DELETE.

Thanks for the tip, I'll definitely be using this. Fear of accidental rm -rf * keeps me up sometimes.

Looks like you need to know about the 'sleep' command...

unzip; strip; touch; finger; grep; mount; fsck; more; yes; fsck; fsck; umount; sleep

`fc` helps. Setting `FCEDIT=ed` helps a lot.

This command can be dangerous itself.

For those who don't know... "The fc utility lists or edits and reexecutes, commands previously entered to an interactive sh."