How to use bash to touch and ln array elements?

Question

I created the following code:

#!/bin/bash

rdir="~/bin/Test/"
echo $rdir
echo $rdir"folderA"
/bin/mkdir -p $rdir"folderA"

# files is an array. () is used to enclose array elements and 
#       each array element enclosed by "".  
files=(
"Apple"
"Apple\ Pie")

IFS="" # What is this for?

for f in ${files[@]}
do
   echo "$rdir${f}"
   /bin/touch "$rdir${f}"
   /bin/ln -s "$rdir${f}" "$rdir${f}"_linktarget"   
   /bin/ln -s "$rdir${f}" "$rdirfolderA"${f}"_linktarget"   

done

I call this code test2.sh and get the below results after executing it:

$ ./test2.sh 
~/bin/Test/
~/bin/Test/folderA
./test2.sh: line 22: unexpected EOF while looking for matching `"'
./test2.sh: line 25: syntax error: unexpected end of file
$ ls -a
~  .  ..  test2.sh

Problems:

• The mkdir -p command did not create the folder.
• The touch command could not create files named according to the array elements. One of the array element contains two words with a space between them. I created the for loop to handle such array elements following the answer of Khushneet.
• I could not create soft link of the touch files and its target in the current directory or the sub-directory "folderA".

Questions:

• How to solve these 3 problems.

• What is IFS and how to use it?

Thanks.

Answer 1

These would be your final script (based on Shellcheck).

#!/bin/bash

rdir="$HOME/bin/Test/"  
# The original statment was  rdir="~/bin/Test/"
# You  need to use $HOME, as ~ doesn't expand inside double quotes
echo "$rdir" #enclosed the whole variable in double quotes
rdirfolderA="$rdir"/folderA #added this line
/bin/mkdir -p "$rdirfolderA" 
#ihave put $rdir inside quotes to prevent word splitting and globbing

# files is an array. () is used to enclose array elements and 
#       each array element enclosed by "".  
files=(
"Apple"
"Apple\ Pie")
#It is recommended to store the old IFS like this
IFS_old="$IFS"
IFS="" # What is this for? Sets the field separator to null
#you need this because you don't have a separating character between the
#strings in the array

for f in "${files[@]}"   #Double quote array expansions to avoid re-splitting elements.
do
   echo "$rdir${f}" 
   /bin/touch "$rdir${f}"
   /bin/ln -s "$rdir${f}" "$rdir${f}"_linktarget   # Removed the  additional double-quote at the end.
   /bin/ln -s "$rdir${f}" "$rdirfolderA/${f}"_linktarget   
done
#Restore the old IFS
IFS="$IFS_old"
#Do something else with your script.

Answer 2

Few syntax errors I can spot .. (hope this helps)

/bin/mkdir -p $rdir"folderA"

--> Change to /bin/mkdir -p "${rdir}folderA"

... Then the following sym-links, a similar change again

/bin/ln -s "$rdir${f}" "$rdir${f}"_linktarget"   
/bin/ln -s "$rdir${f}" "$rdirfolderA"${f}"_linktarget"

--> Change to:

/bin/ln -s "${rdir}${f}" "${rdir}${f}_linktarget"   
/bin/ln -s "${rdir}${f}" "${rdir}folderA${f}_linktarget" 

... Essentially there is a slight difference between $var and ${var}, esp. when used in string-concatenation.

Answer 3

#!/bin/bash

rdir="~/bin/Test/"
echo $rdir
echo $rdir"folderA"
/bin/mkdir -p ${rdir}"folderA"

# files is an array. () is used to enclose array elements and
#       each array element enclosed by "".
files=(
"Apple"
"Apple\ Pie"
"Mango")

IFS="" # What is this for?

for f in ${files[@]}
do
   echo "${rdir}${f}"
   /bin/touch "${rdir}${f}"
   /bin/ln -s $rdir${f} $rdir${f}"_linktarget"
   /bin/ln -s ${rdir}${f} ${rdirfolderA}${f}"_linktarget"

done

Result:

lrwxrwxrwx  1 monk monk      16 May  7 00:33 Apple_linktarget -> ~/bin/Test/Apple
lrwxrwxrwx  1 monk monk      21 May  7 00:33 Apple\ Pie_linktarget -> ~/bin/Test/Apple\ Pie
lrwxrwxrwx  1 monk monk      16 May  7 00:33 Mango_linktarget -> ~/bin/Test/Mango

Answer 4

The Working Script:

#!/bin/bash

rdir=$HOME"/bin/Test/"
echo $rdir
echo $rdir"folderA"
/bin/mkdir -p $rdir"folderA"

# files is an array. () is used to enclose array elements and 
#       each array element enclosed by "".  
files=(
"Apple"
"Apple Pie")

IFS="" 

for f in ${files[@]}
do
   echo $rdir${f}
   /bin/touch $rdir${f}
   /bin/ln -s $rdir${f} $rdir${f}"_linktarget"   
   /bin/ln -s $rdir${f} $rdir"folderA/"${f}"_linktarget"   

done

Answers:

1. It was wrong to say mkdir -p $rdir"folderA" command did not create the folder "folderA". The folder was created as $HOME/bin/Test/~/bin/Test/folderA. However, this was not the intent. It was needed as $HOME/bin/Test/folderA. The mistake arouse because as pointed out by @sjsam "~ doesn't expand inside double quotes" and variable $HOME should have been used to indicate home directory.
2. Problem 2 & 3 occurred because of typo on " as mentioned by @shelter, @Jonathan Leffler and @sjsam, and the overzealous use of "". By limiting the use of "" to string instead of using it to enclose $variable and ${array} was sufficient to get the script to work.
3. The backslash \ typically used in command line to handle space in file names such as in "Apple\ Pie" was redundant, i.e. "Apple Pie" is sufficient as IFS="" was used.

Version of Bash used to execute the script:

$ bash --version
GNU bash, version 4.3.42(1)-release (x86_64-pc-linux-gnu)
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

I like to thanks all answer contributors for their quick responses. :)