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If I alias a keyword, I can't figure out how to bypass it.

$ alias if='echo "GOTCHA!"; if'

$ if true; then echo y; fi
GOTCHA!
y

The usual tools for bypassing an alias, like escaping, command, and builtin, don't work.

$ \if true; then echo y; fi
bash: syntax error near unexpected token `then'

$ 'if' true; then echo y; fi
bash: syntax error near unexpected token `then'

$ command if true; then echo y; fi
bash: syntax error near unexpected token `then'

$ builtin if true; then echo y; fi
bash: syntax error near unexpected token `then'

I would use unalias, but the thing is, I'm putting this code in a function that specifically gets info about aliases (among other commands in an interactive session), so I can't just unset it.

$ unalias if  # or `unalias -a` to be indiscriminate

$ if true; then echo y; fi
y

$ alias if  # I still want to see how the alias is defined, but now it's gone.
bash: alias: if: not found

So, how can I bypass an alias that overrides a keyword, without fully unsetting it?

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  • Follow-up question: Why does Bash allow aliasing a "reserved word" in the first place? According to this question: Use shell reserved word if hidden by an alias, this is a bug in Bash and Zsh, while other shells behave according to the POSIX standard (which specifies more logical behaviour IMO: keywords can't expand as aliases). Zsh has an option to get around this, but I don't see one mentioned for Bash. Commented Aug 27, 2025 at 3:24

2 Answers 2

Reset to default
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It seems to me to be a rather bad idea to make an alias that hides a keyword. Functions in shell components and scripts that the user of your script might want to load after running your code will "randomly" (from the user's perspective) break!

So, honestly, from a programmer's perspective, the answer to your question is: You really simply shouldn't be aliasing keywords like if; the solution is not to temporarily disable aliases globally (which is another thing with side effects, though less likely as severe), but to pick any other possible word. Sometimes, even if we don't like the specific shape an aspect of an environment takes (here: the meaning of a keyword), it's not appropriate to bend it, as it has side effects. The cure here is worse than the disease could be.

Aliases are doubly bad in this context: they are expanded by default in interactive shells, but not in noninteractive ones. Imagine the pain you're causing by allowing the user to do one thing manually on their shell, but it stops working as soon as they put it in a script, or vice versa!

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  • Thanks, and you're right, but this is beside the point. It's not really my intention to alias keywords; I'm asking in case this happens by accident, like, hypothetically, if I forget that time is a keyword and I write an alias like say, alias time='date "+%T"' # Get time of day. This question was prompted by someone on Reddit finding out that one of their tools was overriding the builtin cd in their environment, which is equally insane. Commented Aug 26, 2025 at 18:09
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    in that situation, you do unset the alias. Whatever "needed" that has had it expanded already. Commented Aug 26, 2025 at 18:13
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    Well, like I said, I'm writing a tool that gets info about aliases, so I would want to leave it defined so that I can get info about it, like where it might have been defined. But working around that might turn out to be more effort than it's worth, time will tell. Commented Aug 26, 2025 at 18:50
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    @wjandrea I get you! honestly, I'd just unalias every single keyword from a list of keywords: for keyword in $(compgen -k) ; do unalias "$keyword" 2> /dev/null ; done. Frankly, other things rewording aliases is really just other scripts breaking your shell, my immediate reaction would be to grep for alias .*=.* in all external scripts, and comment that … matter of unpleasant smell out, and see what breaks. Commented Aug 26, 2025 at 20:41
  • Yeah, instead of disabling expansion, I'm considering just checking if any keywords have aliases and erroring out. Commented Aug 26, 2025 at 23:23
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Disable alias expansion with shopt -u expand_aliases

$ shopt -u expand_aliases

$ if true; then echo y; fi
y

$ alias if  # The alias can still be viewed
alias if='echo "GOTCHA!"; if'

You can always re-enable it later with shopt -s:

$ shopt -s expand_aliases

$ if true; then echo y; fi
GOTCHA!
y

Docs

This answer was implied by the manual:

Aliases are not expanded when the shell is not interactive, unless the expand_aliases shell option is set using shopt (see The Shopt Builtin).

Drawbacks

This covers all commands, not just one problematic one. E.g.

$ alias py
alias py='python -q'

$ if true; then py; fi
bash: py: command not found

(Thankfully, this isn't a problem in my case.)

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  • P.S. Normally I wouldn't post a question if I found the answer in the docs, but this one wasn't laid out explicitly. Commented Aug 26, 2025 at 16:28
  • Note that aliases are expanded in functions on definition, not on run. This is making things tricky for implementing this in my code, but hopefully I'll have an update soon. I'm not going to accept this answer until I figure it out. Commented Aug 26, 2025 at 16:34

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