variable substitution

[Kris_5]

Hello Folks,

The following problem I am facing is very silly.

I am trying to get the value of variable
$script from a text file.

See below

$ script=$(grep "^#/script=" tcrontab2958.txt|cut -f2 -d=)
$
$ echo $script
$OC_APPL/xibs/prs_exec.sh


$ cat $script
cat: Cannot open $OC_APPL/xibs/prs_exec.sh: No such file or directory

------------
But both the variable $OC_APPL and file prs_exec.sh are present.
---------------

$ echo $OC_APPL
/opt/ORACLE/oclin/40/dev/aot
$ ll $OC_APPL/xibs/prs_exec.sh
-rwxr-x--- 1 opapps oclin 0 Dec 5 16:25 /opt/ORACLE/oclin/40/h

The question is why the variable $script is unable to substitute the variable $OC_APPL in its value.

TIA,

Kris

[Mark Greene_1]

change:

script=$(grep "^#/script=" tcrontab2958.txt|cut -f2 -d=)

to:

script=`grep "^#/script=" tcrontab2958.txt|cut -f2 -d=`

also check to see the working directory is appropriate for the file, or add the full pathname if you can.

--
mark

[maria paschali]

Hi,

I don't know if you checked this, but see if your permissions and groups are correct.

It might not be able to see the file because you don't have read access to that file because it is owned by another user and or is in another group.

I hope this helps

Maria

[Kris_5]

Yes, I have privileges to see the file and the file is existing in the present directory. See the results of commands following the cat $script command. Thanks,

[Mark Greene_1]

sorry, I missed this bit:

The question is why the variable $script is unable to substitute the variable $OC_APPL in its value

You need to use "eval" to get the shell to do the substitutio of $OC_APPL before it assigns it to $script.

--
mark

[Kris_5]

Hi,

It is not working that way. See below. Thanks,

$ `grep "^#/script=" tcrontab2958.txt|cut -f2 -d=`
sh: $OC_APPL/xibs/prs_exec.sh: not found.

$ eval `grep "^#/script=" tcrontab2958.txt|cut -f2 -d=`

$ eval $(grep "^#/script=" tcrontab2958.txt|cut -f2 -d=)

$ script=$(eval `grep "^#/script=" tcrontab2958.txt|cut -f2 -d=`)
$ echo $script


$ cmd=`grep "^#/script=" tcrontab2958.txt|cut -f2 -d=`
$ script=`eval $cmd`
$ echo $script

Kris

[Darrell Allen · Accepted solution]

Hi Kris,

Instead of cat $script try:

cat `eval echo $script`

Darrell

[Mark Greene_1]

Sorry for not being clearer, this line:

script=`grep "^#/script=" tcrontab2958.txt|cut -f2 -d=`

will extract the line from file tcrontab2958.txt that matches the grep. In reading your last response, am I correct in thinking that this line will contain the text OC_APPL? If so, then there is no way to get the shell to evaluate that, as it is just sees that as text.

If OC_APPL is a valid variable within the script that is doing the above grep, then you can put it together with the $script variable like:

script=$OC_APPL$script.

If this does not correctly address the situation, perhaps if you could post the line from the file you are grepping out, that would help.

--
mark

[Deepak Extross]

Would it be possible to modify your tcontab file to replace
"$OC_APPL/xibs/prs_exec.sh" with "${OC_APPL}/xibs/prs_exec.sh " ?

[Steven Sim Kok Leong]

Hi Kris,

Use a combination of sed and xargs. I have tested it to work for your case. In the below testing, the variable OC_APPL contains the path of subdirectory a.

=====================================
$ echo $OC_APPL
a
$ echo $script
$OC_APPL/xibs/prs_exec.sh
$ echo $script|sed -e "s/\$OC_APPL/$(echo $OC_APPL)/g"|xargs ls
a/xibs/prs_exec.sh
$ echo $script|sed -e "s/\$OC_APPL/$(echo $OC_APPL)/g"|xargs cat
correct
=====================================

Hope this helps. Regards.

Steven Sim Kok Leong
Brainbench MVP for Unix Admin
http://www.brainbench.com

[Steven Sim Kok Leong]

Hi,

What Darrell suggested will also work. His method is much neater than mine.

=========================================
$ echo $script
$OC_APPL/xibs/prs_exec.sh
$ cat `eval echo $script`
correct
=========================================

Hope this helps. Regards.

Steven Sim Kok Leong
Brainbench MVP for Unix Admin
http://www.brainbench.com