Manage Unix rights reading dynamic field in a csv file in bash - bash

Question

i'm currently stuck with a bash script that should be able to manage permission on files and directories at the end of the processing part.
Actually i have 4 components:
the main script which source .conf file and libs (.sh), process things, and call a function "ApplyPermissionFromCSVFile" with a .csv file as argument at the end, to ensure that rights are correctly set. This function should handle the job for managing permission on files
a script called "permission_lib.sh" which contains several functions, including the "ApplyPermissionFromCSVFile" one. This script is SOURCED at the begining of main script
a .conf file which contains some path defined as variables which is SOURCED at the beginning of main script
a .csv file containing paths (including "dynamic path", which refer to variables defined in conf file) for files and directories which is READ by the ApplyPermissionFromCSVFile function
At the moment, the main script runs correctly, is able to source both conf file and lib file but when i put some debug point inside the "ApplyPermissionFromCSVFile", it appears that "dynamic path" is not interpreted by bash.
Extract of Main Script:
#########################################
includes
##################################################
# this section can _almost_ be copied as-is ;-)
nameOfThisScript=$(basename "${BASH_SOURCE[0]}")
directoryOfThisScript="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
configFile="$directoryOfThisScript/$nameOfThisScript.conf"
functionsFile="$directoryOfThisScript/safeScriptsFunctions.sh"
permissionLib="$directoryOfThisScript/permission_lib.sh"
permissionFile="$directoryOfThisScript/$nameOfThisScript.permissionFile.csv"
for fileToSource in "$configFile" "$functionsFile" "$permissionLib"; do
source "$fileToSource" 2>/dev/null || {
echo "File '$fileToSource' not found"
exit 1
}
done
#Main Loop to read CSV File is called in permissionLib.sh
ApplyPermissionFromCSVFile $permissionFile
Extract of conf file (real filename replaced for exemple):
totovariable="/usr/local"
tatavariable="$totovariable/bin"
Extract of csv file:
$totovariable;someuser;somegroup;0600
$tatavariable;someuser;somegroup;0600
Extract of permission lib file:
function ApplyPermissionFromCSVFile {
local csvFileName="$1"
local fieldNumberFileName=1
local fieldNumberOwner=2
local fieldNumberGroupOwner=3
local fieldNumberPermissions=4
while read csvLine
do
fileName=$(getFieldFromCsvLine "$fieldNumberFileName" "$csvLine")
fileOwner=$(getFieldFromCsvLine "$fieldNumberOwner" "$csvLine")
fileGroupOwner=$(getFieldFromCsvLine "$fieldNumberGroupOwner" "$csvLine")
filePermissions=$(getFieldFromCsvLine "$fieldNumberPermissions" "$csvLine")
permissionArray[0,0]="$fileName|$fileOwner|$fileGroupOwner|$filePermissions"
echo "${permissionArray[0,0]}"
done < "$csvFileName"
}
getFieldFromCsvLine() {
csvFieldSeparator=';'
fieldNumber="$1"
csvLine="$2"
echo "$csvLine" | cut -d "$csvFieldSeparator" -f "$fieldNumber"
}
Don't bother for the fact that the loop overwrite value at each iterations, it's not the purpose here (but optionnal answer :p).
Which output results:
$totovariable|someuser|somegroup|0600
$tatavariable|someuser|somegroup|0600
Changing owner to someuser:somegroup for file $tatavariable
chown: cannot access '$tatavariable': No such file or directory
Changing permissions to 0600 for file $tatavariable
chmod: cannot access '$tatavariable': No such file or directory
After some investigations an research, it seems normal as:
conf file is SOURCED (by main script)
lib file is SOURCED (by main script)
csv file is not SOURCED but READ (by function in lib). So bash consider the variables contents as "pure-string", and not variables
The issue, is that i can't clearly see how and where i should replace the "pure-string" variable by its value (defined in .conf file and sourced by main script): at the main script level ? at the lib level with global variables ?
Actual solutions that i've found:
sed substitute
use eval
Any help could be appreciated.

Answer 1

Solution used:
fileName=eval echo "$fileName"
As the pathes in .csv file may contain "$" Symbol, Bash parameter expansion will not work in every case.
Exemple:
with the following csv content:
$tatavariable;someuser;somegroup;0600
$totovariable/thisotherfile.txt;someuser;somegroup;0660
$totovariable;someuser;somegroup;0600
/home/someuser/lolzy.txt;someuser;somegroup;0666
And the following conf file:
totovariable="/home/someuser/fack"
tatavariable="$totovariable/thisfile.txt"
The following bash code (based on eval which is not highly recommended in most case) will work on every case (containing $ symbol or not):
#!/bin/bash
#########################
# Function
#########################
getFieldFromCsvLine() {
local csvFieldSeparator=';'
local fieldNumber="$1"
local csvLine="$2"
echo "$csvLine" | cut -d "$csvFieldSeparator" -f "$fieldNumber"
}
#########################
#Core Script
#########################
source configFile.conf
csvFileName="permissionFile.csv"
fieldNumberFileName=1
fieldNumberOwner=2
fieldNumberGroupOwner=3
fieldNumberPermissions=4
while read csvLine
do
fileName=$(getFieldFromCsvLine "$fieldNumberFileName" "$csvLine")
fileOwner=$(getFieldFromCsvLine "$fieldNumberOwner" "$csvLine")
fileGroupOwner=$(getFieldFromCsvLine "$fieldNumberGroupOwner" "$csvLine")
filePermissions=$(getFieldFromCsvLine "$fieldNumberPermissions" "$csvLine")
#Managing Variables used as 'Dynamic path'
fileName=$(eval echo "$fileName")
echo "Content of \$fileName is $fileName"
done < "$csvFileName"
Results:
[someuser#SAFEsandbox:~]$ ./simpletest.sh
Content of $fileName is /home/someuser/fack/thisfile.txt
Content of $fileName is /home/someuser/fack/thisotherfile.txt
Content of $fileName is /home/someuser/fack
Content of $fileName is /home/someuser/lolzy.txt
Whereas the following bash code (base on bash parameters expansion) will throw errors:
#!/bin/bash
#########################
# Function
#########################
getFieldFromCsvLine() {
local csvFieldSeparator=';'
local fieldNumber="$1"
local csvLine="$2"
echo "$csvLine" | cut -d "$csvFieldSeparator" -f "$fieldNumber"
}
#########################
#Core Script
#########################
source configFile.conf
csvFileName="permissionFile.csv"
fieldNumberFileName=1
fieldNumberOwner=2
fieldNumberGroupOwner=3
fieldNumberPermissions=4
while read csvLine
do
fileName=$(getFieldFromCsvLine "$fieldNumberFileName" "$csvLine")
fileOwner=$(getFieldFromCsvLine "$fieldNumberOwner" "$csvLine")
fileGroupOwner=$(getFieldFromCsvLine "$fieldNumberGroupOwner" "$csvLine")
filePermissions=$(getFieldFromCsvLine "$fieldNumberPermissions" "$csvLine")
#Managing Variables used as 'Dynamic path'
fileName=${!fileName}
echo "Content of \$fileName is $fileName"
done < "$csvFileName"
Behaviour example when .csv contains $ symbol:
[someuser#SAFEsandbox:~]$ ./simpletest.sh
./simpletest.sh: line 35: $tatavariable: bad substitution
Behaviour example when you remove the $ symbol in .csv file, but there is still incremental path notions in it:
[someuser#SAFEsandbox:~]$ ./simpletest.sh
Content of $fileName is /home/someuser/fack/thisfile.txt
./simpletest.sh: line 35: totovariable/thisotherfile.txt: bad substitution
Using bash parameter expansion (which is recommended in most case) is not easy here, because it forces to manage 2 cases in the script:
path containing a leading $ or serveral $ (contatenated variables paths)
path not containing a leading $ or serveral $ (contatenated variables paths)
Regards