It makes no sense to put a background statement in backticks, is the problem. How could it possibly set the variable until the process completes? So it either it fills the variable with a blank and puts the program in the background, or waits anyway. Neither gets you what you want.
You could replace the sleep with :, which will cause it to just loop forever until either condition breaks the loop. This will cause 100% CPU usage while it's waiting for the timeout. If you run your script with 'nice ./script.sh' that may be tolerable.
Since it needs to be POSIX you'll have to replace my math statement too.
I have a command which will run fine in a unix command prompt. Can you tell how to interprete this command inside perl script......
The command is :
perl -pe 's/(\|333\}.*)\}$/$1|1.6}/' FIA.txt
This will search for the number 333 and appends 1.6 at the end of that line....... (1 Reply)
I'm new to Linux. I have a bash script that invokes an executable. I'd like use the SCRIPT command inside the script and exit out of the script command after it writes to the file. Does this make sense? Below is an example of the contents of my script.
#BEGIN SCRIPT
script typescript... (6 Replies)
Hi everyone,
when executing this command in unix:
echo "WM7 Fatal Alerts:", $(cat query1.txt) > a.csvIt works fine, but running this command in a shell script gives an error saying that there's a syntax error.
here is content of my script:
tdbsrvr$ vi hc.sh
"hc.sh" 22 lines, 509... (4 Replies)
Hi All,
Is there any way to monitor a command inside shell script ? I have a script inside which I have a tar command which zips around 200GB data.
tar zcvf $Bckp_Dir/$Box-BaseBackup-$Day.tar.gz * --exclude 'dbserver_logs/*' --exclude postmaster.pid --exclude 'pg_xlog/*'
I want to... (3 Replies)
Hi,
I have a script file in server A. Inside the script file, I first have a ssh command that will connect to a remote server B. In the same script file itself, I have a sequence of commands that has to be run in server B. I am embedding these commands in the script file that I have in server A.... (2 Replies)
hii,,
I am trying to automate jira. during my scripting using bash script, in the terminal i got the terminal message like this:
"Configure which ports JIRA will use.
JIRA requires two TCP ports that are not being used by any other
applications on this machine. The HTTP port is where you... (1 Reply)
Hi ,
DIR1 has only one file with .txt extension , trying to get the size of that file using the following script
#!/bin/ksh
foldr_1="/etc/DIR1"
#echo "$foldr_1"
sze_fdr1=$(ls -ltr foldr_1/*.txt |awk '{ print $5 }')
echo "$sze_fdr1"
After executing the above script getting... (1 Reply)
hi,
how can i know whether a command inside an sftp script has failed or not?
i have a sftp expect script
#!/usr/bin/expect
spawn /usr/bin/sftp abc@ftp.abc.com
expect "sftp>"
send "cd dir\r"
expect "sftp>"
send "mput abc.txt\r"
expect "sftp>"
send "mput def.xls\r"
expect "sftp>"... (5 Replies)
My script needs to take a folder path to the location of a C program, and run the program until the user selects exit in his C program. The script needs to create a transcript to a text file while the C program is running.
Creating a transcript can be easily done with the script command but it... (2 Replies)
Discussion started by: syntax_eror
2 Replies
LEARN ABOUT CENTOS
vwait
vwait(n) Tcl Built-In Commands vwait(n)
__________________________________________________________________________________________________________________________________________________NAME
vwait - Process events until a variable is written
SYNOPSIS
vwait varName
_________________________________________________________________DESCRIPTION
This command enters the Tcl event loop to process events, blocking the application if no events are ready. It continues processing events
until some event handler sets the value of variable varName. Once varName has been set, the vwait command will return as soon as the event
handler that modified varName completes. varName must be globally scoped (either with a call to global for the varName, or with the full
namespace path specification).
In some cases the vwait command may not return immediately after varName is set. This can happen if the event handler that sets varName
does not complete immediately. For example, if an event handler sets varName and then itself calls vwait to wait for a different variable,
then it may not return for a long time. During this time the top-level vwait is blocked waiting for the event handler to complete, so it
cannot return either.
EXAMPLES
Run the event-loop continually until some event calls exit. (You can use any variable not mentioned elsewhere, but the name forever
reminds you at a glance of the intent.)
vwait forever
Wait five seconds for a connection to a server socket, otherwise close the socket and continue running the script:
# Initialise the state
after 5000 set state timeout
set server [socket -server accept 12345]
proc accept {args} {
global state connectionInfo
set state accepted
set connectionInfo $args
}
# Wait for something to happen
vwait state
# Clean up events that could have happened
close $server
after cancel set state timeout
# Do something based on how the vwait finished...
switch $state {
timeout {
puts "no connection on port 12345"
}
accepted {
puts "connection: $connectionInfo"
puts [lindex $connectionInfo 0] "Hello there!"
}
}
SEE ALSO
global(n), update(n)
KEYWORDS
event, variable, wait
Tcl 8.0 vwait(n)