Backticks are evil

echo "The date is: $(date +%D)"
This is a simple example of using proper command nesting using $() over ``. There are a number of advantages of $() over backticks. First, they can be easily nested without escapes: program1 $(program2 $(program3 $(program4))) versus program1 `program2 \`program3 \`program4\`\`` Second, they're easier to read, then trying to decipher the difference between the backtick and the singlequote: `'. The only drawback $() suffers from is lack of total portability. If your script must be portable to the archaic Bourne shell, or old versions of the C-shell or Korn shell, then backticks are appropriate, otherwise, we should all get into the habit of $(). Your future script maintainers will thank you for producing cleaner code.

By: atoponce
2009-03-07 15:51:59

What Others Think

I totally agree.
CodSpirit · 641 weeks and 3 days ago
That's why rc shell uses `{}, $ is too confusing too
maht · 641 weeks and 3 days ago
linuxrawkstar · 641 weeks and 3 days ago
@maht, i agree: echo "The date is: {date +%D}" would be easier. i wish i could do this in bash.
nickleus · 606 weeks ago
Bad example; it doesn't need command substitution: date +"The date is %c" (Not to mention that %D is the worst possible date format.)
cfajohnson · 604 weeks and 4 days ago
@cfajohnson cute, but the purpose of the command is to show how to appropriately nest commands, not how to use the date command.
atoponce · 574 weeks and 4 days ago
Yeah, evil but totally necessary. For example, this won't work with $() but works just fine with back ticks: x=1; case $x in 1) echo one ;; esac Why? Because the 1) in the case confuses the $() parser.
zapatar · 437 weeks and 2 days ago
@zapatar, in my FreeBSD, your example runs perfectly in the $() version: $(x=1; case $x in 1) echo ls ;; esac) as well as the backtick version `x=1; case $x in 1) echo ls ;; esac`
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What do you think?

Any thoughts on this command? Does it work on your machine? Can you do the same thing with only 14 characters?

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