Does anyone know why the below script is not working? Why is not the variable tot_files updated?
Because you updated it in a subshell. In fact it is updated - but only in the subshell and with leaving the subshell the value is lost too.
These two are identical and they:
tell the shell to open a new shell and execute everything within the braces in this new shell and then close it.
The next problem is:
This is not working at several levels.
First: what do you want to assign to the variable tot_files? Obviously the stdout of whatever is inside the subshell ( "$(...) ). It is like this:
The shell opens a subshell and executes echo "blabla" in this subshell. So you get some output at <stdout>, in this case a string. This output is then assigned to the variable.
The next thing is you put that assignment into background:
But an assignment is not a separate process, it is done within the shell internally. x=5 does not generate a process you could put into background (which is in fact just another way of saying it runs asynchronously to the main process). I am not sure about that (perhaps Don Cragun knows more about these fringe situations) but i suppose that the "&" is simply ignored in this case.
The next problem is:
A pipeline takes the <stdout> (the "normal" output) of a process and feeds it into the input (<stdin>) of another process. The output of
is <nothing>. Try it out on the commandline. When you pour that nothing into another command, what will happen, hmm? Furthermore, the wait command does not even process any input, and neither does it have any output. So, even if there would be any output from the assignment operation it would be lost by now - for the same reasons as above. So, whatever you pipe the output of wait into, there will be nothing to process because there will be no output.
Now, after this lengthy explanation of what will not work, let us finish on some positive note:
In principle you do that the following way: first display the message for the user that he should wait, then you start the lengthy process. Finally you update (or maybe redraw, depending on which possibilities are offered by your environment) the screen with a finishing message and the result of the operation:
As an addendum i suggest to go over the counting command itself too (to me that looks not ideal, whatever it is supposed to do), but since i do not know exactly what you want to achieve i will not suggest an alternative yet. You are welcome to post your goals and we can do that too.
Hi All,
I need to pass a variable to perl script from bash script, where in perl i am using if condition. Here is the cmd what i am using in perl
FROM_DATE="06/05/2008"
TO_DATE="07/05/2008"
"perl -ne ' print if ( $_ >="$FROM_DATE" && $_ <= "$TO_DATE" ) ' filename"
filename has... (10 Replies)
Hi,
I use AIX (ksh) and Linux (bash) servers. I'm trying to do scripts to will run in both ksh and bash, and most of the time it works. But this time I don't get it in bash (I'm more familar in ksh).
The goal of my script if to read a "config file" (like "ini" file), and make various report.... (2 Replies)
Hello all,
I'm working on a script, and as part of it, I'm trying to create a loop that will run through a stored piece of information a certain number of times pulling out information, and each time create a variable with a unique name that will store that information. I'm sure it's a simple... (3 Replies)
Hello all,
I have this shell script, but do not understand why the variables inside the if block does not keep its value outside. Is it because of the pipe ? How can i fix this problem ?
Thank you for helping.
local alarm=""
local num_alarm=0
local -a alarms
... (3 Replies)
Hello,
I am struggling with using variable made using "eval".
a=4
eval b$a=20
echo $b$a ???
As shown above, I am trying to call back the variable "bX" assuming I do not know the value of "a".
How can I do that?
I tried several combinations but nothing worked.
Thanks (10 Replies)
Hi,
I wrote the following program to understand mutexes. If I run the program , number of threads is shown as zero, even after creating one thread. When running with gdb, it works fine.
The function process is used to update global variable (used to keep track of threads). It looks like the... (2 Replies)
#aa=xxxx
#zz="cc $aa"
#aa=gggg
#echo $zz
out put is
cc xxxx
if I want to get
cc gggg
how should I do, I don't want to write zz="c $aa " after aa=gggg (2 Replies)
Hello,
Can I ask how to expand variable that contains another in bash? I need to loop variable within another one like this:
RD1=testgrp
RD2=testgroup
RD3=testgroupfile
RD4=tstgroup
...
RD40=try2013
DEST=/home/king/finaldir
for i in {1..40}; do
mv ${RD${i}} ${DEST}
done
I do not... (8 Replies)
Hi Team
In the below code, irrespective of the if statement that gets executed, retcd is being assigned a standard value(1) instead of changing as per code. Could you please help to see where is it going wrong.
rval=0
CONF_FILE=/apps/wmroot/scripts/props/UMPath.properties
NOHUP="nohup"... (3 Replies)