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Environment Variable with Special characters

 
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# 1  
Old 05-20-2012
Variable with Special characters
Hello all,

I am facing with a problem of invoking an environment variable.

If I use this command :
Code:
/bin/ls -lt FILE_NM_?(20120515|20120516)??????_sas.sig | head -n1 | awk '{print $9}'

It perfectly outputs the desired result.
Code:
FILE_NM_20120516000000_sas.sig

But if I do this:
Code:
FILE_ARG=FILE_NM_?(20120515|20120516)??????_sas.sig

and then do this:
Code:
/bin/ls -lt $FILE_ARG | head -n1 | awk '{print $9}'


The last code doesnt work.


Any help is appreciated!
Last edited by Franklin52; 05-21-2012 at 05:42 AM.. Reason: Please use code tags
# 2  
Old 05-20-2012
This is file matched by the shell at the time you create it.
Code:
FILE_ARG=FILE_NM_?(20120515|20120516)??????_sas.sig

This is not
Code:
FILE_ARG='FILE_NM_?(20120515|20120516)??????_sas.sig'

This last example is then used this way:
Code:
ls -l $FILE_ARG

which expands the variable into a valid filename.
# 3  
Old 05-21-2012
Hi Jim,

Thank-you for the response!

Here's how I tried:
Code:
> FILE_ARG=FILE_NM_?(20120515|20120516)??????_sas.sig'

and then
Code:
> /bin/ls -lt $FILE_ARG | head -n1 | awk '{print $9}'


The message I am getting is:
FILE_NM_?(20120515|20120516)??????_sas.sig not found


Even though there are 2 files available in the same directory. Am I doing something wrong here!
Last edited by Franklin52; 05-21-2012 at 05:43 AM.. Reason: Please use code tags
# 4  
Old 05-21-2012
Quote:
Originally Posted by jim mcnamara
Code:
FILE_ARG='FILE_NM_?(20120515|20120516)??????_sas.sig'

Quote:
Originally Posted by sethmj
> FILE_ARG=FILE_NM_?(20120515|20120516)??????_sas.sig'
Do you see where you went wrong? (Hint: Highlighted in red above) Or is this a typo??
# 5  
Old 05-21-2012
BALAJESURI,

Sorry about this, but it was a typo in the posting and not the actual code.

The acual code did had:

Code:
FILE_ARG='FILE_NM_?(20120515|20120516)??????_sas.sig'

I am still facing the same error:

Code:
FILE_ARG_?(20120515|20120516)??????_sas.sig not found



Thank-you for the response!
Last edited by Scott; 05-21-2012 at 05:13 PM.. Reason: Code tags
# 6  
Old 05-21-2012
What shell are you using? I'm only famaliar with bash, but I think you're using ksh. Seems the expansions are done in different order.

bash:
Code:
[mute@geek ~/temp/sethmj]$ shopt -s extglob
[mute@geek ~/temp/sethmj]$ FILE_ARG=FILE_NM_?(20120515|20120516)??????_sas.sig
[mute@geek ~/temp/sethmj]$ echo "$FILE_ARG"
FILE_NM_?(20120515|20120516)??????_sas.sig
[mute@geek ~/temp/sethmj]$ ls -lt $FILE_ARG
-rw-r--r-- 1 mute mute 0 May 21 15:46 FILE_NM_20120515000000_sas.sig
-rw-r--r-- 1 mute mute 0 May 21 15:44 FILE_NM_20120516000000_sas.sig

ksh:
Code:
$ FILE_ARG=FILE_NM_?(20120515|20120516)??????_sas.sig
$ echo "$FILE_ARG"
FILE_NM_?(20120515|20120516)??????_sas.sig
$ ls -lt $FILE_ARG
ls: cannot access FILE_NM_?(20120515|20120516)??????_sas.sig: No such file or directory
$ ls -lt FILE_NM_?(20120515|20120516)??????_sas.sig
-rw-r--r-- 1 mute mute 0 May 21 15:46 FILE_NM_20120515000000_sas.sig
-rw-r--r-- 1 mute mute 0 May 21 15:44 FILE_NM_20120516000000_sas.sig

Neither does filename expansion on variable assignment. Except with arrays:

Code:
$ files=( FILE_NM_?(20120515|20120516)??????_sas.sig ); echo "${files[@]}"
FILE_NM_20120515000000_sas.sig FILE_NM_20120516000000_sas.sig

edit: If you're looking for the latest file matching the glob, try:

Code:
unset latest
for file in FILE_NM_?(20120515|20120516)??????_sas.sig
do
  [[ $file -nt $latest ]] && latest=$file
done
 
echo "$latest"

Last edited by neutronscott; 05-21-2012 at 01:07 PM..
This User Gave Thanks to neutronscott For This Post:
sethmj
# 7  
Old 05-21-2012
hello Neurtonscott,

It works fine... but can you explain what this code is doing?


unset latest
Code:
for file in FILE_NM_?(20120515|20120516)??????_sas.sig
do
  [[ $file -nt $latest ]] && latest=$file
done

Especially the switches and the content withing the do loop!

Moderator's Comments:
Mod Comment Please use code tags
Last edited by Scott; 05-21-2012 at 05:14 PM.. Reason: Code tags
 
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