redirecting to a temp file

ZAMO · 01-31-2009, 12:46 AM

Hi all,

Got struck with a logic. We used to store values in variables, which are stored in memory and not written to Hard disk.

say

Code:

my_varialbe=`ls -l |awk '{print $9}' |grep myfile`

I used to store a set of file names to a file and then recall them . There is a way to store the set of file names as it is and call them whenever needed . I want to store a file on memory and to recall it. How can I Do that?
say

Code:

`ls -l |awk '{print $9}' |read this to a file

will give a list of files and I just want to read it into a file and want to read the lines one by one , if needed.
How can I do that ?

Thanks

colucix · 01-31-2009, 03:12 AM

Your description is not really clear, this time. Can you elaborate a bit more, please? What do you mean for "read to a file"? Usually you can read FROM a file and write TO a file. I'm missing something. Anyway, if the problem is to read a file line by line, you should already know that a simple while loop does the trick:

Code:

while read line
do
  echo "$line"
done < file

syg00 · 01-31-2009, 03:20 AM

I agree with colucix (now you have both an Italian *and* an Aussie confused ...

)
To write the data to a file, do you want something like this ???.

Code:

ls -l |awk '{print $9}' > outfile.txt

Then you can read it back later as per colucix post.

ZAMO · 01-31-2009, 03:25 AM

Thanks Colucix

Here is an example of what am trying to do:

Code:

$ pwd
/etc/sysconfig
$ ls -l |awk '{print $9}'
auditd
authconfig
autofs
bluetooth
clock
console
crond
desktop
diskdump
dund

I want to store the above output as it is. so am doing

Code:

 ls -l |awk '{print $9}' >testfile

The testfile will be written to the disk. Instead I want to store it memory(without writing it to disk) and want to call the file lines one by one.

Is there a way?

colucix · 01-31-2009, 05:13 AM

Maybe using something like process substitution?

Code:

while read fname
do
  echo "$fname"
done < <(ls -1)

In this way the output of ls -1 (note this is a -one not -el, which achieves the same result as your command) is processed in real time. Instead, if you want to store the list of files somewhere for later use, you can just assign the output of ls -1 to a variable and then reference that variable to retrieve the previously created list of files. For example:

Code:

my_list=$(ls -1)
<some other stuff here>
<and some time later...>
for fname in $(echo $my_list)
do
  echo "$fname"
done

ZAMO · 01-31-2009, 05:33 AM

Got that exactly. Thanks