bash script with double for loop over multiple arrays with access to array names

Question

I'm using rsync to copy specific files from a source directory (and subdirectories) to a destination directory (and subdirectories). The mapping of the subdirectories is not identical, so I'm defining arrays of subdirectories of the destination directory that contain the source file paths.

I've been unable to successfully loop over the destination arrays with access to the names of the arrays. Here's a MWE (filenames and directories must be edited, obviously).

#!/bin/bash

sourcedir=~/Dropbox/230/
destdir=~/Dropbox/230/website/

# Destination arrays
organization=(
syllabus/syllabus.pdf
)

notes=(
notes/ME230_2014S_Part0_Lec00.pdf
notes/ME230_2014S_Part1_Lec01_partial.pdf
)

echo "synchronizing: rsyncing from $sourcedir to $destdir"


for destsubdir in $organization $notes
do
  for sourcesubdir in "${destsubdir[@]}"
  do
    echo "from $sourcedir$sourcesubdir to $destdir$destsubdir/"
    rsync -avz "$sourcedir$sourcesubdir" "$destdir$destsubdir/"
  done
done

This is obviously wrong because I don't want the destination to be the contents of $destsubdir but the name of the variable itself. I've been unable to successfully achieve this.

Note that a proper solution would allow any number of arrays to included without restructuring (e.g. no extra for-loops).

If multi-indexed arrays were possible in bash, this would be much easier, I think. Thanks for any help!

Solution

@jeanrjc has a good solution. Here's what it looks like in terms of my example above.

#!/bin/bash

sourcedir=~/Dropbox/230/
destdir=~/Dropbox/230/website/

# Destination arrays
organization=(
  syllabus/syllabus.pdf
)

notes=(
  notes/ME230_2014S_Part0_Lec00.pdf
  notes/ME230_2014S_Part1_Lec01_partial.pdf
)

destsubdirArray=(
  organization
  notes
)

echo "synchronizing: rsyncing from $sourcedir to $destdir"

for destsubdir in ${destsubdirArray[*]}
do
  destsubdirContents=$destsubdir[@];
  for sourcesubdir in ${!destsubdirContents}
    do
    echo "from $sourcedir$sourcesubdir to $destdir$destsubdir/"
    rsync -avz "$sourcedir$sourcesubdir" "$destdir$destsubdir/"
  done
done

@jeanrjc I would like to see, for instance, from Users/picone/Dropbox/230/syllabus/syllabus.pdf to Users/picone/Dropbox/230/website/organization/. — Rico Picone
– Rico Picone, Commented Apr 3, 2014 at 17:38
hmmm, I don't get it. why Users/picone/Dropbox/230/website/organization/ ? Can you just re-write the question with simple example, and a clear explanation of the expected behavior ? Did you check my answer btw? does it help ? — jrjc
– jrjc, Commented Apr 3, 2014 at 18:29
@jeanrjc I think your answer works, but I haven't checked it yet. It appears to be correct, given the output you've shown. I'm evaluating dave-sines answer because it's an interesting trick. However, I think yours is probably the most kosher. I'll probably mark it as the accepted answer once I test it. Thanks for the help! — Rico Picone
– Rico Picone, Commented Apr 3, 2014 at 18:59

jrjc · Accepted Answer · 2014-04-03 14:29:54Z

4

I'm not sure I get what you meant, but maybe this can help you :

one=( "one" 5 6 7 8 )
two=( "two" 11 22 33 )
three=( "tree" 777 888 999 )
all=( one two three )

for i in ${all[*]}; do 
  ref=$i[@]; 
  for j in ${!ref}; do 
      echo $j
   done
done

one
5
6
7
8
two
11
22
33
tree
777
888
999

answered Apr 3, 2014 at 14:29

jrjc

22.1k10 gold badges67 silver badges79 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

dave sines · Accepted Answer · 2014-04-03 15:24:01Z

1

Bash 4.3 supports namerefs -- the expansion of a nameref is the expansion of the nameref's contents rather than the nameref itself (it may help to think of namerefs as being similar to symlinks).

declare -n destsubdir

for destsubdir in organization notes ; do
  for sourcesubdir in "${destsubdir[@]}" ; do
    echo "$sourcedir$sourcesubdir $destdir$sourcesubdir"
  # rsync -avz "$sourcedir$sourcesubdir" "$destdir$sourcesubdir"
  done
done

unset -n destsubdir

For earlier bash versions the nearest equivalent is, as kisp states, to eval the entire inner loop. The quoting requirements can get out of hand really quickly.

for destsubdir in organization notes ; do
  eval 'for sourcesubdir in "${'"$destsubdir"'[@]}" ; do
          echo "$sourcedir$sourcesubdir" "$destdir$sourcesubdir"
  #        rsync -avz "$sourcedir$sourcesubdir" "$destdir$sourcesubdir"
        done'
done

Note: those rsync commands have not been tested.

answered Apr 3, 2014 at 15:24

dave sines

111 bronze badge

1 Comment

Rico Picone Over a year ago

Your answer is intriguing. I tried to update bash to 4.3, but brew only took me to 4.2.45, which doesn't recognize namerefs.

kisp · Accepted Answer · 2014-04-03 14:28:52Z

0

Solution to pass the variable names instead of the variables :

You can pass the variable names itself to the first for, then evaluate them in the second if needed.

like

for var_name in variable1 variable2 ; do
eval "myvar=\$$var_name"

Anyway, the single for loop can be used with the elements only if you use ${array[@]} everywhere.

edited Apr 3, 2014 at 14:28

answered Apr 3, 2014 at 14:23

kisp

6,5723 gold badges23 silver badges19 bronze badges

Collectives™ on Stack Overflow

bash script with double for loop over multiple arrays with access to array names

Solution

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

Solution

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related