# How to parse config variables from external file to shell script

**URL:** <https://community.unix.com/t/how-to-parse-config-variables-from-external-file-to-shell-script/172829>\
**Category:** Shell Programming and Scripting\
**Created:** [July 8, 2007, 11:52am UTC](https://community.unix.com/t/how-to-parse-config-variables-from-external-file-to-shell-script/172829 "2007-07-08T11:52:07Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![pradsh](https://community.unix.com/letter_avatar/pradsh/32/6_449c533f586939b6e5f246632a46421f.png) [@pradsh](https://community.unix.com/u/pradsh)\
**Post date:** [July 8, 2007, 11:52am UTC](https://community.unix.com/t/how-to-parse-config-variables-from-external-file-to-shell-script/172829/1 "2007-07-08T11:52:07Z")

</div>

How do i use a config.txt to recursively pass a set of variables to a shell script

eg my config.txt looks like this :

[set\_1]  
path=c://dataset/set1  
v1= a.bin  
v2= b.bin

[set\_2]  
path=c://dataset/set2  
v1= xy.bin  
v2= abc.bin

[set\_3]  
..................

and so on .

and my testscript :

#!/bin/bash  
.$1

echo $path $v1 $v2

Right now I am able to parse first set of variables . How do i move on to the subsequent set\_2 , set\_3 ...........

Thanks in advance  
pradsh

---

<div class="post-metadata">

**Author:** ![aigles](https://community.unix.com/user_avatar/community.unix.com/aigles/32/118_2.png) [@aigles](https://community.unix.com/u/aigles)\
**Post date:** [July 9, 2007, 8:24am UTC](https://community.unix.com/t/how-to-parse-config-variables-from-external-file-to-shell-script/172829/2 "2007-07-09T08:24:55Z")

</div>

You can do something like that :

```nohighlight
# Function: get_config_list config_file
          # Purpose : Print the list of configs from config file
get_config_list()
{
   typeset config_file=$1

   awk -F '[][]' '
      NF==3 && $0 ~ /^\[.*\]/ { print $2 }
   ' ${config_file}
}

# Function : set_config_vars config_file config [var_prefix]
# Purpose : Set variables (optionaly prefixed by var_prefix) from config in config file
set_config_vars()
{
   typeset config_file=$1
   typeset config=$2
   typeset var_prefix=$3
   typeset config_vars

   config_vars=$( 
        awk -F= -v Config="${config}" -v Prefix="${var_prefix}" '
        BEGIN { 
           Config = toupper(Config);
           patternConfig = "\\[" Config "]";
        }
        toupper($0) ~ patternConfig,(/\[/ && toupper($0) !~ patternConfig) { 
           if (/\[/ || NF <2) next;
           sub(/^[[:space:]]*/, "");
           sub(/[[:space:]]*=[[:space:]]/, "=");
           print Prefix $0;
        } ' ${config_file} )

   eval "${config_vars}"
}

#
# Set variables for all config from config file
#
file=config.txt
for cfg in $(get_config_list ${file})
do
   echo "--- Configuration [${cfg}] ---"
   unset $(set | awk -F= '/^cfg_/ { print $1 }') cfg_
   set_config_vars ${file} ${cfg} cfg_
   set | grep ^cfg_
done

```

Input file (config.txt)

```nohighlight
[set_1]
path=c://dataset/set1
v1= a.bin
v2= b.bin

[set_2]
path=c://dataset/set2
v1= xy.bin
v2= abc.bin

[set_3]
v1 = value1

```

Output:

```nohighlight
--- Configuration [set_1] ---
cfg_path=c://dataset/set1
cfg_v1=a.bin
cfg_v2=b.bin
--- Configuration [set_2] ---
cfg_path=c://dataset/set2
cfg_v1=xy.bin
cfg_v2=abc.bin
--- Configuration [set_3] ---
cfg_v1=value1

```

---

<div class="post-metadata">

**Author:** ![edcrosbys](https://community.unix.com/letter_avatar/edcrosbys/32/6_449c533f586939b6e5f246632a46421f.png) [@edcrosbys](https://community.unix.com/u/edcrosbys)\
**Post date:** [July 9, 2007, 2:21pm UTC](https://community.unix.com/t/how-to-parse-config-variables-from-external-file-to-shell-script/172829/3 "2007-07-09T14:21:52Z")

</div>

Since you aren't worried about accessing the First Set of Variables again, you can just source the second set... Using your example:

[set\_1]  
path=c://dataset/set1  
v1= a.bin  
v2= b.bin

[set\_2]  
path=c://dataset/set2  
v1= xy.bin  
v2= abc.bin

[set\_3]  
..................

and so on .

and my testscript :

#!/bin/bash  
.$1 #Here you are sourcing set 1 - I assume

echo $path $v1 $v2 #here you are showing the variables

. $2 #Here you are sourcing set 2  
echo $path $v1 $v2 #here you are showing the new variables

# Just make sure to call the script with the variable files as the first and second argument.