# MacOS case insensitive file system

**URL:** <https://community.keyboard.io/t/macos-case-insensitive-file-system/958>\
**Category:** Off topic\
**Created:** [January 26, 2018, 8:17am UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958 "2018-01-26T08:17:02Z")\
**Posts on this page:** 19\
**Page:** 1

<div class="post-metadata">

**Author:** ![noseglasses](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/noseglasses/32/429_2.png) [@noseglasses](https://community.keyboard.io/u/noseglasses)\
**Post date:** [January 26, 2018, 8:17am UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/1 "2018-01-26T08:17:02Z")

</div>

Unfortunately, I do not have access to any Apple products, nor do I know anyone who owns an Apple. Nevertheless, I want to add MacOS support (travis testing with MacOS) to one of my projects.

As far as I can see, most MacOS systems are by default case insensitive. Because of that, I need a shell command that can be passed the absolute path to a file and that returns the path of the file with proper case.

Say, there is a file `/aBc/Def.txt` and I know that the lower case representation of the filename’s full path is `/abc/def.txt`. Thus, what I want is

```bash
> <magiccommand> /abc/def.txt
/aBc/Def.txt

```

EDIT 1: Maybe `ls /abc/def.txt` is enough, but I just can’t check. Can someone try that, please.

Any help highly appreciated.

---

<div class="post-metadata">

**Author:** ![merlin](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/merlin/32/3416_2.png) [@merlin](https://community.keyboard.io/u/merlin)\
**Post date:** [January 26, 2018, 1:05pm UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/2 "2018-01-26T13:05:27Z")

</div>

Unfortunately, `ls foo/bar` will always output `foo/bar`, even if the filename is `FOO/bAr`. However, with `bind "set completion-ignore-case on"`, tab completion will correct the case of filenames on HFS+. I’m not sure how bash/readline does that, but it’s a place to start looking.

---

<div class="post-metadata">

**Author:** ![merlin](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/merlin/32/3416_2.png) [@merlin](https://community.keyboard.io/u/merlin)\
**Post date:** [January 26, 2018, 1:10pm UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/3 "2018-01-26T13:10:35Z")

</div>

GNU Emacs `M-x find-file` tab completion also corrects case on case-insensitive filesystems, but if I recall correctly, you prefer vi, so maybe that’s not helpful. I’d look at the code, but I don’t have time today, I’m afraid.

I’ll check back here, though; I’m sure I can run tests occasionally on an HFS+ filesystem if you think you’ve got a solution.

[Big thumbs down to case-insensitive filesystems, by the way. Boo!]

---

<div class="post-metadata">

**Author:** ![noseglasses](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/noseglasses/32/429_2.png) [@noseglasses](https://community.keyboard.io/u/noseglasses)\
**Post date:** [January 26, 2018, 2:32pm UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/4 "2018-01-26T14:32:14Z")

</div>

Yes, at least from a developer point of view, case-insensitive filesystems are pretty anoying.  
Unfortunately, I think Emacs and vi are no solution for my problem as I need some type of command that I can call from CMake. One that is available on any fresh MacOS system. After searching the web up and down I gave up and implemented a brute force recursive token-wise path comparison in CMake.

Thanks anyway.

---

<div class="post-metadata">

**Author:** ![merlin](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/merlin/32/3416_2.png) [@merlin](https://community.keyboard.io/u/merlin)\
**Post date:** [January 26, 2018, 3:06pm UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/5 "2018-01-26T15:06:06Z")

</div>

Oh, I didn’t mean that you could _use_ Emacs to perform the conversion – I was thinking the source code might reveal a good way to do it.

---

<div class="post-metadata">

**Author:** ![merlin](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/merlin/32/3416_2.png) [@merlin](https://community.keyboard.io/u/merlin)\
**Post date:** [January 26, 2018, 3:26pm UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/6 "2018-01-26T15:26:11Z")

</div>

I don’t know why I didn’t think of this right away:

```auto
#!/bin/sh

DIR=$(dirname "${1}")

FILENAME=$(ls "${DIR}" | grep -i "${1}")

```

The argument to `grep` needs some escaping to handle some unusual filenames, of course, but this approach does work.

---

<div class="post-metadata">

**Author:** ![noseglasses](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/noseglasses/32/429_2.png) [@noseglasses](https://community.keyboard.io/u/noseglasses)\
**Post date:** [January 26, 2018, 3:56pm UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/7 "2018-01-26T15:56:27Z")

</div>

Does your shell skript assume `${1}` to be an absolute path? I tried it (on Linux) but it did not work.

I cannot see how grep-ing the absolute path in the path name returned by `ls ${DIR}` is supposed to work. Isn’t `ls ${DIR}` at most a substring of `${1}` and not vice versa? Probably I am missing something.

---

<div class="post-metadata">

**Author:** ![merlin](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/merlin/32/3416_2.png) [@merlin](https://community.keyboard.io/u/merlin)\
**Post date:** [January 26, 2018, 4:00pm UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/8 "2018-01-26T16:00:32Z")

</div>

No, `$1` is a relative pathname. I grep the dir listing (case-insensitive) to get just the filename of interest.

---

<div class="post-metadata">

**Author:** ![merlin](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/merlin/32/3416_2.png) [@merlin](https://community.keyboard.io/u/merlin)\
**Post date:** [January 26, 2018, 4:06pm UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/9 "2018-01-26T16:06:18Z")

</div>

Oh, sorry; that script just gets the relative filename, not the absolute path.

---

<div class="post-metadata">

**Author:** ![merlin](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/merlin/32/3416_2.png) [@merlin](https://community.keyboard.io/u/merlin)\
**Post date:** [January 26, 2018, 4:19pm UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/10 "2018-01-26T16:19:08Z")

</div>

A slightly better version:

```bash
#!/bin/sh

D=$(dirname "${1}")
F=$(basename "${1}")

(
    cd "${D}"
    REGEX='^'
    REGEX+="${F}"
    REGEX+='$'

    FILENAME=$(ls | grep -i "${REGEX}")

    echo $FILENAME
)

```

---

<div class="post-metadata">

**Author:** ![merlin](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/merlin/32/3416_2.png) [@merlin](https://community.keyboard.io/u/merlin)\
**Post date:** [January 26, 2018, 6:35pm UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/11 "2018-01-26T18:35:11Z")

</div>

I couldn’t get this off my mind, so here’s a much better version:

```bash
#!/bin/sh

get_canonical_name () {
    dir=$(dirname "${1}")
    file=$(basename "${1}")

    cd "${dir}"
    regexp='^'
    regexp+="${file}"
    regexp+='$'

    canonical_name=$(ls -1 | grep -i "${regexp}")
    
    echo "${canonical_name}"
}

D=$(dirname "${1}")
F=$(basename "${1}")

cd "${D}"

PATH_ELEMENTS=$(pwd | tr '/' '\n')/${F}

ABS_NAME=''
for dir in ${PATH_ELEMENTS}; do
    ABS_NAME+='/'
    ABS_NAME+=$(get_canonical_name "${ABS_NAME}/${dir}")
done

echo "${ABS_NAME}"

```

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<div class="post-metadata">

**Author:** ![buc](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/buc/32/523_2.png) [@buc](https://community.keyboard.io/u/buc)\
**Post date:** [January 26, 2018, 10:46pm UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/12 "2018-01-26T22:46:19Z")

</div>

No offense intended, but using the supplied filename as a regex gave me the hebbie-jebbies.

Also, it broke when given a path or filename containing a space.

Therefore I propose the following:

```auto
#!/bin/sh

get_canonical_name () {
    D=$(dirname "${1}")
    I=$(stat -f '%i' "${1}")
    R=$(ls -1ia "${D}" | grep "^ *${I} " | sed "s/^ *${I} //")

    if ["${C}"]
    then
        C="${R}/${C}"
    else
        C="${R}"
    fi

    if ["${D}" != '.']
    then
        get_canonical_name "${D}"
    fi
}

G="${1}"

if [-e "${G}"]
then
    C=""
    get_canonical_name "${G}"
    echo "${C}"
fi

```

It uses the inode number (guaranteed to be unique with a directory) to match up the supplied name and the version returned by a `ls` of the containing directory.

---

<div class="post-metadata">

**Author:** ![merlin](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/merlin/32/3416_2.png) [@merlin](https://community.keyboard.io/u/merlin)\
**Post date:** [January 26, 2018, 10:51pm UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/13 "2018-01-26T22:51:33Z")

</div>

Oh, certainly; I didn’t have sufficient time to make it robust. I do think you shouldn’t use `$C` like that, though; better to make it the second argument to `get_canonical_name`.

---

<div class="post-metadata">

**Author:** ![buc](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/buc/32/523_2.png) [@buc](https://community.keyboard.io/u/buc)\
**Post date:** [January 26, 2018, 11:32pm UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/14 "2018-01-26T23:32:34Z")

</div>

> [@merlin](#):
>
> I do think you shouldn’t use $C like that, though

This is shell. All of the variables, including `$1` and `$2` are global. Since their globalness can’t be avoided, it might as well be embraced, right? 🙂

From a certain perspective there’s danger in writing code that disguises the fact that the variables are global, especially with a recursive function. `$C` was the only variable that was being used in a way that required it to be global, making it stand out.

But, I also noticed that my original version went into an infinite loop when given an absolute path name, so since I had to update it anyway I went ahead and modified it as you suggested.

One minor bug: if it is given a filename with one (or more) leading `./` it will strip off the first one (i.e. `./foo` will become `foo` and `././bar` will become `./bar`). I can’t see an easy way to eliminate it so I have left it alone.

```sh
#!/bin/sh

get_canonical_name () {
    D=$(dirname "${1}")
    I=$(stat -f '%i' "${1}")
    C=$(ls -1ia "${D}" | grep "^ *${I} " | sed "s/^ *${I} //")

    if ["${2}"]
    then
        C="${C}/${2}"
    fi

    if ["${D}" = "/"]
    then
        echo "/${C}"
    elif ["${D}" = '.']
    then
        echo "${C}"
    else
        get_canonical_name "${D}" "${C}"
    fi
}

G="${1}"

if [-e "${G}"]
then
    get_canonical_name "${G}" ""
fi

```

---

<div class="post-metadata">

**Author:** ![merlin](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/merlin/32/3416_2.png) [@merlin](https://community.keyboard.io/u/merlin)\
**Post date:** [January 27, 2018, 6:00am UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/15 "2018-01-27T06:00:24Z")

</div>

> [@buc](#):
>
> This is shell. All of the variables, including $1 and $2 are global.

Not true, at least in `bash`, which is the default `/bin/sh` on macOS. Try this:

```bash
#!/bin/sh

testprint () {
    echo $1
}
echo $1
testprint foo
echo $1

```

`$1` is a local variable in the function. There’s also `local`…

There’s no need for this script to be universal; it has a very specific purpose, for a particular OS, where `bash` is the default shell. There’s no need for any of these shenanigans on Linux or \*BSD systems, so it’s really pointless to insist on POSIX compliance.

---

<div class="post-metadata">

**Author:** ![buc](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/buc/32/523_2.png) [@buc](https://community.keyboard.io/u/buc)\
**Post date:** [January 29, 2018, 2:15pm UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/16 "2018-01-29T14:15:35Z")

</div>

Portability is a major concern at my day job. It’s a habit I like to keep in practice on. 🙂

---

<div class="post-metadata">

**Author:** ![cyrossignol](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/cyrossignol/32/1179_2.png) [@cyrossignol](https://community.keyboard.io/u/cyrossignol)\
**Post date:** [April 1, 2018, 8:37am UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/17 "2018-04-01T08:37:04Z")

</div>

> [@buc](#):
>
> This is shell. All of the variables, including $1 and $2 are global. Since their globalness can’t be avoided, it might as well be embraced, right?

Just out of curiosity…I’m not aware of any shells that place a function’s positional parameters back in the global scope. Is there a shell that does this? If so, I imagine that writing for such a shell would actually diminish a script’s portability because every other shell scopes function parameters locally.

---

<div class="post-metadata">

**Author:** ![cyrossignol](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/cyrossignol/32/1179_2.png) [@cyrossignol](https://community.keyboard.io/u/cyrossignol)\
**Post date:** [April 1, 2018, 8:49am UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/18 "2018-04-01T08:49:20Z")

</div>

By the way @noseglasses, for simple cases, we don’t need to wrap the command if we’re using Bash. We can let the shell do the work with globbing:

`<command> /a[Bb]c/[Dd]ef.txt`

Course, this will match both _/abc/def_ and _/aBc/Def_ if they both exist, but I’m guessing this probably isn’t the case.

If you’ve got a Windows box, you can test on the case-insensitive filesystem in a [Cygwin](https://cygwin.org) environment.

---

<div class="post-metadata">

**Author:** ![buc](https://yyz1.discourse-cdn.com/flex031/user_avatar/community.keyboard.io/buc/32/523_2.png) [@buc](https://community.keyboard.io/u/buc)\
**Post date:** [April 2, 2018, 1:04pm UTC](https://community.keyboard.io/t/macos-case-insensitive-file-system/958/19 "2018-04-02T13:04:15Z")

</div>

I don’t recall, and I don’t have access to those systems any more. I spent a lot of time, mostly in korn shells, on several proprietary UNIXes, ending most of a decade ago.

Old habits die hard.