Problems with variables syntax

Shell Programming and Scripting
1

Hi there

I am really struggling :eek: to place a value in a variable with the following loop, having run out of ideas please can someone point me in the right direction?

We first read two PIDs of a program (say calc) into an array, then we loop reading the details of those processes into a value which increments each time the loop runs.

I just can't get proc$val to equal the output from`ls -ld /proc/${array[$val]}`

One example of how I have tried (and failed is below)

val=0
for i in {1..${array
[*]}}
do
 
[ "proc$val"="`ls -ld /proc/${array[$val]}`" ]
 
((val++))
done
2 
val=0
for i in ${array
[*]}
do
    proc$val="$(ls -ld /proc/$i)" # Check if you really want this to be ls -ld.
    ((val++))
done
3

use

$((val++))

instead of this

((val++))
4

Hi thanks for the reply

just tried in ksh enviroment

$proc$val="$(ls -ld /proc/9467)"
Error
ksh: proc0=dr-xr-xr-x 8 nathan nathan 0 2012-04-27 08:09 /proc/9467: not found [ no such file or directory]

if I omit the proc$val ie

$proc0="$(ls -ld /proc/9467)"

it works!

5

Try creating an array instead of multiple variables like proc0,proc1..etc

 
val=0
for i in ${array
[*]}
do
    proc_output[$val]="$(ls -ld /proc/$i)" 
    ((val++))
done
6

Just to be clear, the reason that:

for i in {1..${array[*]}}

Doesn't work is that brace expansion is the first thing that the shell tries to process *before* it's converted the variable into an actual value. So in the shell's "mind" you're trying to say for everything between 1 and the word "${array...}" which obviously doesn't make any sense.

7

Back to my original issue, just forget the loop for now

just can't get proc$val to equal the output from `ls -ld /proc/${array[$val]}`

I found the following did work

 eval 'proc'$val=`'ls -ld /proc/{$array[$val]}'`

however I just want the time stamp from this string

 eval 'proc'$val=`'ls -ld /proc/{$array[$val]} | awk ' {print $7}' '`

fails

 awk: line 2: missing } near end of file

is this even possible? any ideas would be gratefullly recieved :slight_smile: