A simple question, but I can't find the answer. the zsh documentation overwhelms me :-(

function z ()
  echo ${1:s/the/THE}

$ z thethethe


How can I get all 'the' to be replaced with 'THE', not just the first occurrence? With zsh it's the easiest things that seem to be the hardest to find examples for.

5 Answers 5


This is a history expansion modifier, so add the g modifier immediately before s.

print -r -- ${1:gs/the/THE}

Alternatively, use the parameter expansion syntax where a double slash means a global substitution. In this case, the part after // is a wildcard pattern, whereas history expansion substitution takes a literal string (unless the histsubstpattern option is enabled).

print -r -- ${1//the/THE}

This should do the job:

print -r -- ${VARIABLE//the/THE}

Thereyago, it had to be simple:

print -r -- ${1//the/THE}

... the double slash does it, and you can't fool around with " :s "

BTW, I'd sure like to thank the 'StackExchange' sites for existing. Of all the zillions of places one might ask a question, these are by far the best--one not only almost always gets answers, but those answers are invariably of the highest quality.


There are many answers, but none of them are comprehensive, so I felt like adding an answer that sums it all up.


If you are trying to uppercase the string, the simplest way is to use:

> str="thethethe"
> upper="$str:u"
> echo $upper

(Not part of the original question, but just in case) If you are trying to lowercase, the same goes for :l.

Replacing substrings

If you want to replace a single occurrence, use this:

> str="thethethe"
> echo ${str/the/man}

If you add an extra slash between the variable and the test to substitute, it will replace all the occurrences:

> str="thethethe"
> echo ${str//the/man}

Another option is to use the history modifiers, just like Gilles suggested:

> str="thethethe"
> echo ${str:gs/the/man}

// works perfect if you're only trying to replace a specific word to all caps while leaving the rest of it untouched. If you are trying to convert everything to uppercase, you can use ":u" on the variable

print -r -- $SOME_ENV_VALUE:u # outputs: THETHETHE

You can verify which modifiers you have available in the zsh expansion and substitution manual

man zshexpn

Or with

info zsh modifiers 

If you have the info pages installed.

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