How do you wait for command substitution processes to complete?
When running a command using the >(cmd) syntax in bash how do you wait for the command to complete before moving on in your script?
Here is a simple example:
This produces the output:
My objective is to guarantee echo "WORLD" gets printed after all of the >() processes are done.
The bigger picture is that I have a lot of large log files to process through a variety of log parsers and using this syntax does have the positive effect of reading the files from disk once to process them in parallel in many sub processes taking advantage of multi-core CPUs. Everything works fine except for the fact that I can't tell when those processes are done.
I can think of one solution where I could have my log processing scripts write an "I'm Done" message to a file or pipe somewhere for the parent to loop listening for.
I'm using PERL on windows NT to try to run an extract of data. I have multiple zip files in multiple locations. I am extracting "*.t" from zip files and subsequently adding that file to one zip file so when the script is complete I should have one zip file with a whole bunch of ".t" files in it.
... (2 Replies)
I am attempting within a for-loop, to have my shell script (Solaris v8 ksh) wait until a copy file command to complete before continueing. The specific code is:
for files in $(<inputfile.lst)
do
mv directory/$files directory/$files
ksh -m -i bg %%
wait $!
done
I am shaky on the... (3 Replies)
Does anyone have an example of a korn shell scripts kicking of multiple background processes and then using the wait command to get the return code from those processes?
I want to write a program that kicks off multiple Oracle procedures and then wait for the return code before I procede.... (1 Reply)
As far as I can tell, the bash wait command waits for a logical "AND" of all the child processes.
Assuming I am coding in C:
(1) What is the function I would use to create multiple bash child process running perl?
(2) What is the function I would use to reinvent the bash wait command so I... (4 Replies)
Did not use 'wait' yet.
How I understand by now the wait works only for child processes, started background.
Is there any other way to watch completion of any, not related process (at least, a process, owned by the same user?)
I need to start a background process, witch will be waiting... (2 Replies)
Hi All,
Am finding performance of my SD card using hdparm.
hdparm -tT /dev/BlockDev0
/dev/BlockDev0:
Timing cached reads: 1118 MB in 2.00 seconds = 558.61 MB/sec
HDIO_DRIVE_CMD(null) (wait for flush complete) failed: Inappropriate
ioctl for device
Timing buffered disk reads: 14... (0 Replies)
Hi, Is there any way to know the child process status as and when it finished. If i write like below
nohup sh a1.sh & ### has sleep 20 ;echo a1.sh
nohup sh a2.sh & ### has sleep 10 ;echo a2.sh
nohup sh a3.sh & ### has sleep 5 ;echo a3.sh
wait
This will wait till a1.sh ,a2.sh a3.sh... (0 Replies)
Let's say I start process A.sh, then start process B.sh. I call both of them in my C.sh
How can I make sure that B starts its execution only after A.sh finishes.
I have to do this in loop.Execution time of A.sh may vary everytime.
It is a parameterized script. (17 Replies)
Hi All,
I have a question related to Shell scripting. In my shell script, I have following two commands in sequence:
sed 's/^/grep "^120" /g' $ORIGCHARGEDAMTLIST|sed "s;$;| cut -f$FIELD_NO1 -d '|' | awk '{ sum+=\$1} END {printf (\"%0.2f\\\n\", sum/100)}' >$TEMPFILE
mv $TEMPFILE $ORIGFILE... (3 Replies)
Hello,
im having bash script with
while ***
command1 &&
command2 &&
command3 &&
done
i want to ask how i can prevent overloading server, by waiting untill all commands complete? any low resources intensive command like "wait" - i dont know if exist? (2 Replies)
Discussion started by: postcd
2 Replies
LEARN ABOUT V7
fork
FORK(2) System Calls Manual FORK(2)NAME
fork - spawn new process
SYNOPSIS
fork( )
DESCRIPTION
Fork is the only way new processes are created. The new process's core image is a copy of that of the caller of fork. The only distinc-
tion is the fact that the value returned in the old (parent) process contains the process ID of the new (child) process, while the value
returned in the child is 0. Process ID's range from 1 to 30,000. This process ID is used by wait(2).
Files open before the fork are shared, and have a common read-write pointer. In particular, this is the way that standard input and output
files are passed and also how pipes are set up.
SEE ALSO wait(2), exec(2)DIAGNOSTICS
Returns -1 and fails to create a process if: there is inadequate swap space, the user is not super-user and has too many processes, or the
system's process table is full. Only the super-user can take the last process-table slot.
ASSEMBLER
(fork = 2.)
sys fork
(new process return)
(old process return, new process ID in r0)
The return locations in the old and new process differ by one word. The C-bit is set in the old process if a new process could not be cre-
ated.
FORK(2)