Shell Programming and Scripting

Hi Grasper,

I like your thinking, the problem I have is that in trying to simplify the issue so I don't put pages of coding on here, is that the issue is missed!

I tried your script and it works, however its in a slightly different context from mine.

In my script, the pattern_002=* is within a configuration file and a generic search of the configuration file is the way the pattern is pulled back.

The actual code from my script is a function which is launched as follows

fn_read_config "$v_search" "$v_iter" 002

in this case v_search is pattern and v_iter is 002

function fn_read_config {

p_search_item=$1
p_iteration=$2

grep ^"$p_search_item"_"$p_iteration" "$c_config_dir/$c_config_file" >/dev/null
v_search_return_code=$?

if [ $v_search_return_code -eq 0 ]
then
v_search_return=`grep ^"$p_search_item"_"$p_iteration" "$c_config_dir/$c_c
onfig_file"`
v_search_line=`print ${v_search_return#*=}`
return 0
fi
}

from this I wanted v_search_line to be *
I can't use the noglob when doing the search as I need the variables to be expanded.

I hope you understand, I did want to keep this as simple as possible!

Cheers
Helen

Hi Bakunin,

Thanks for your reply. The pattern may not always be a * so I could not run sed on it every time. I cannot check to see if the pattern is a * as it has already been evaluated!

Cheers
Helen

Hi Helen

I think the issue with variable-expansion and noglob is only a problem when doing your 'eval'. Setting noglob to on shouldn't affect it otherwise. I think I'm roughly using your code-structure in the following:-

#!/bin/ksh

function fn_read_config {

p_search_item=$1
p_iteration=$2

grep ^"$p_search_item"_"$p_iteration" ./paramfile >/dev/null
v_search_return_code=$?


if [ $v_search_return_code -eq 0 ]
then
v_search_return=`grep ^"$p_search_item"_"$p_iteration" ./paramfile`
set -o noglob
v_search_line=`print ${v_search_return#*=}`
echo "PATTERN $v_search_line"
set +o noglob
return 0
fi
}

v_search=pattern
v_iter=002

fn_read_config "$v_search" "$v_iter"

set -o noglob
echo "PATTERN $v_search_line"
set +o noglob

And I'm still able to get the output:-

PATTERN *
PATTERN *

I suppose it could depend on how you were using the resulting variable value, but I'm guessing it could still be possible by manipluating noglob.

Cheers

Maybe i don't get your point, but in the code snippet you provided i see several occasions where a quote would help. I tried the following code and it worked for every special char i tried in the input file - even without setting noglob. It should cover all the operations you used in your script save for the eval:

Code:

#!/bin/ksh

function func {

typeset var1="$1"
typeset var2="$2"

print - "Output from func(): var1=\"$var1\"\tvar2=\"$var2\""

return 0
}

# main()

typeset mvar1=""
typeset mvar2=""

cat input_file_with_codes | while read line ; do
     mvar1="$(print - "$line" | sed 's/  */ /g' | cut -d' ' -f1)"
     mvar2="$(print - "$line" | sed 's/  */ /g' | cut -d' ' -f2)"
     print - "mvar1=\"$mvar1\"\tmvar2=\"$mvar2\""
     func "$mvar1" "$mvar2"
done

exit 0

To write a small sed function which escapes every special character for exactly the eval should be no problem:

Code:

#!/bin/ksh

function escape_it {
typeset input="$1"
typeset output=""

output="$(print - "$input" | sed 's/[*?|]/\\&/g')"
print - "$output"

return 0
}

# main()

# ... do whatever ...

tmpvar="$(escape_it "$var")"
eval $tmpvar

# ... rest of your code ...

exit 0

Hi Bakunin and Grasper,

Thank-you both for your help. In the end I pre-parsed the config file with the sed statement to escape any special characters. I then used the resulting output as the config file. This worked fine.

Many thanks for all your time and patience!
Cheers
Helen