Saving directory content to an array (bash)

Question

I need to save content of two directories in an array to compare them later. Thats the solution i write:

DirContent()    
{
        #past '$1' directorys to 'directorys'
        local DIRECTORYS=`ls -l --time-style="long-iso" $1 | egrep '^d' | awk '{print $8}'`
        local CONTENT
        local i
        for DIR in $DIRECTORYS
        do
                i=+1
                CONTENT[i]=${DIR}
        done
        echo $CONTENT
}

Then when I try to print this array I get empty output. Both directories are not empty. Please tell me what am I doing wrong here. Thanks, Siery.

Yes. You have right. 'i=+1' adds element to an array when '((1=i+1))' modify value. Probably next error i make was 'CONTENT[i]' not 'CONTENT[$i]'. But function still returns empty arrays, problem is somewhere else. — , Jan 13 '16 at 04:11
1 = i+1 surely not, 1 can't be the LHS of an assignment. 1 is always 1. — user unknown, Jan 13 '16 at 04:15
You know that 'print $8' will fail if you have blanks in filenames and the like? Can you exclude such patterns? Btw: If your ability to post questions is that much affected by the time, you should go to sleep and ask when fit again. And why don't you use `content=($(ls -l ... '{print $8}')` to create the array? to produce the array? — user unknown, Jan 13 '16 at 04:25
Yes, i was just thinking the same when i look at this code. That i can just write this function in two lines. Any ways, no, i don't know how to fix that problem you mention. I start learning bash 2 days ago. Can you help me with that? This is backup script so i cant know what files am i going to deal with. — , Jan 13 '16 at 04:59
Recommended reading: [BashGuide](http://mywiki.wooledge.org/BashGuide)! — Benjamin W., Jan 13 '16 at 05:42

score 1 · Accepted Answer · edited May 23 '17 at 11:45

The core of this question is answered in the one I marked as a duplicate. Here are a few more pointers:

All uppercase variable names are discouraged as they are more likely to clash with environment variables.
You assign to DIRECTORYS (should probably be "directories") the output of a complicated command, which suffers from a few deficiencies:
- Instead of backticks as in var=`command`, the syntax var=$(command) is preferred.
- egrep is deprecated and grep -E is preferred.
- The grep and awk commands could be combined to awk /^d/ '{ print $8 }'.
- There are better ways to get directories, for example find, but the output of find shouldn't be parsed either.
- You shouldn't process the output of ls programmatically: filenames can contain spaces, newlines, other special characters...
DIRECTORYS is now just one long string, and you rely on word splitting to iterate over it. Again, spaces in filenames will trip you up.
DIR isn't declared local.
To increase i, you'd use (( ++i )).
CONTENT[i]=${DIR} is actually okay: the i is automatically expanded here and doesn't have to be prepended by a $. Normally you'd want to quote your variables like "$dir", but in this case we happen to know that it won't be split any further as it already is the result of word splitting.
Array indices start at zero and you're skipping zero. You should increase the counter after the assignment.
Instead of using a counter, you can just append to an array with content+=("$dir").
To print the contents of an array, you'd use echo "${CONTENT[@]}".

But really, what you should do instead of all this: a call DirContent some_directory is equivalent to echo some_directory/*/, and if you want that in an array, you'd just use

arr=(some_directory/*/)

instead of the whole function – this even works for weird filenames. And is much, much shorter.

If you have hidden directories (names starts with .), you can use shopt -s dotglob to include them as well.

score 0 · Answer 2 · answered Jan 13 '16 at 04:55

0

You can try

        for((i=0;i<${#CONTENT[*]};i++))
        do
             echo ${CONTENT[$i]}
        done

instead of echo $CONTENT

Also these change are required

     ((i=+1))
     CONTENT[$i]=${DIR}

in your above code

answered Jan 13 '16 at 04:55

Varun

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Saving directory content to an array (bash)

2 Answers2