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I have been trying to get this to work for a while now, and I am still confused as to why it doesnt work. I'm trying to add a function to my bashrc to cd down to the next directory that has files or more than one directory in it. But I cant get this test for files to work, and I do not understand the problem. find . -maxdepth 1 -type f works when I type it into the terminal, but here it doesn't seem to be working. And -z should test if it is null, which it should be when Icall it in an empty directory. But it just returns files detected every time... is it the use of the dot operator in doFilesExist? 

function cdwn(){ # check if there are files or multiple directories in current wd doFilesExist="find . -maxdepth 1 -type f" if [ -z '$doFilesExist' ]; then echo "no files detected" else echo "files detected" fi }

Thanks guys, seems to be working with the following:

function cdwn(){ # check if there are files or multiple directories in current wd doFilesExist=`find . -maxdepth 1 -type f` if [ -z "$doFilesExist" ]; then echo "no files detected" else echo "files detected" fi }

But I am not satisfied as I do not understand why I was having problem, can you suggest some guides I can follow to get a better understanding? I clearly have either forgotten or not understood things in the past!

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  • [ -z $var ] checks if the variable var is set or not. In your case there's a string in var so it is always set. -- BTW add double quotes when using unary comparison ([ ... ]). Commented Apr 11, 2015 at 23:02
  • ... so you need double quotes to have the value of $doFileExist interpreted, otherwise it will just check if the string $doFilesExist instead of its value: [ -z "$doFilesExist" ] Commented Apr 11, 2015 at 23:03
  • By the way, instead of editing the post saying "hey this works" you can [also] mark as accepted the answer that solved your issue. This way it is clear to future visitors that your problem is solved to future readers Commented Apr 11, 2015 at 23:09
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    sorry about that, I will make sure to select an answer in future Commented Apr 11, 2015 at 23:23

2 Answers 2

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Looks like wrong quotes. To put a result of bash command to a variable:

doFilesExist=$(find . -maxdepth 1 -type f)

or 

doFilesExist=`find . -maxdepth 1 -type f`

The part with if block should be also changed to [ -z "$doFilesExist" ]: "Inside a single-quoted string nothing(!!!!) is interpreted, except the single-quote that closes the quoting" source.

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3 Comments

In fact you could just say if [ -z "$(find ... )" ], no need to use the variable.
Haha, that's a nice one! Might become unreadable but this is definitely one of the shortest find commands I've ever seen. So no problem there.
In fact, yes. I've marked places to rewrite. Your advice is a good step further. To understand, who it works, you can read about Command substitution.
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You should try the following:

function cdwn(){ # check if there are files or multiple directories in current wd files=$(find . -maxdepth 1 -type f | wc -l) if [[ ${files} -gt 0 ]]; then echo "files detected" else echo "no files detected" fi }

Don't check using -z as it checks if a variable is set or not, it says nothing about the size. Also you just stored a command as a string, it has never been executed. To execute it you could store the content in a variable like some of the other answers suggest but those variables could become incredible large.

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it is a bit overkilling to write into a file
As opposed to putting it all into a variable?
Well maybe it is, I'll remove this answer probably.
Well it is interesting but not very much the way I would do it. Note that counting the number of results of find piping to wc -l can lead to errors if some file names contain new lines (it is weird but it can happen!). But in this case it helps, yes. I would in fact just say if [ -z "$(find ...)" ] to get rid of variables and everything.
Yes exactly, and since it's a subshell exporting didn't help either. So basically I had to resort back to writing to a file, which kind of completes the circle, haha. Anyway, thanks for the tips and pointers, it's always nice to learn!
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