First, note that you can cut a couple of processes out of your pipe line by using:
instead of:
Then a few comments about your C code:
The fork() function returns 0 in the child (if a child is created successfully) and returns the PID of the child in the parent (if a child is created successfully), or returns -1 in the parent (if a child could not be created). Your code assumes that fork() never fails! Don't make that assumption.
Operands like 2>&1, |, and grep are shell directives; not operands to be passed to the lsof utility.
Instead of executing lsof, you probably need to execute sh with arguments -c and lsof 2>&1 | awk '/log/ && /openbox/ && c++ { print $10 }'.
This User Gave Thanks to Don Cragun For This Post:
I have a function that returns a bunch of exit codes, say func1, and in my code I'm trying to execute that function in an if statement. This is the closest I could get.
f1call=`func1 $arg1 $arg2`
if ]; then
...
fi
When I run the script the function never gets called. What's the right way... (7 Replies)
Hi ,
I m actually trying to implement pipes program,but after executing the execvp(),my program is getting hanged up :mad:
Actaully i m getting the desired output expected from execvp()...but once results are displayed on the output screen ,program is getting hanged up
values of... (3 Replies)
In a BASH library I'm creating, I have two functions that look like:
function check_process {
PIDFILE=$1
if ; then
PID=`cat $PIDFILE`
if && ; then
return 1
fi;
fi;
return 0
}
function fork_process {
CMD=$1
PIDFILE=$2
... (2 Replies)
I want to log into a remote server transfer over a new config and then backup the existing config, replace with the new config.
I am not sure if I can do this with BASH scripting.
I have set up password less login by adding my public key to authorized_keys file, it works.
I am a little... (1 Reply)
Hi Folks,
I have a small doubt, the binary commands under /bin and /sbin as well as other path binary files, if you peek deep into that, you can find the difference in the way of normal perl programming and some commands will be like binary files. how are the commands executing like the... (3 Replies)
Hi,
I want to run these two commands one after the other.
awk 'BEGIN {OFS="\t"} {print $2}'
sort -u
rather than typing awk 'BEGIN {OFS="\t"} {print $2}' file1 > file2, then sort -u file2 > file3. Is it possible to run both commands on file1 then get output file3?
Its kinda hard for... (5 Replies)
Hi, I do the following:
i) malloc some parameter structures
ii) fork
iii) in the child, I call execvp using these parameters
obviously, here I can never free() the structures as execvp should not return
iiii) I am currently doing waitpid in parent then freeing, but this does not seem to work... (1 Reply)
I have a script that writes another script with
cat >/usr/local/bin/myscript.sh <<EOF
#!/bin/sh
VAR=`run a command here`
EOF
Problem is, after this is run, I get:
$ cat /usr/local/bin/myscript.sh
#!/bin/sh
VAR=result of command
How do I stop that from happening with Macs... (2 Replies)
Ksh is my default shell, but I want use the bash shell since its convenient to me.
When I type a long command line in a terminal, it does not wrap to the next line when I reach the end of the line and it wraps onto the same line, overwriting my prompt and the rest of what I typed.
$... (5 Replies)
I have a script that checks if the script has been ran with sudo.
If the script is not ran as sudo, the current script is being executed with exec sudo bash.
You are asked for a password, you type in the password, success. Everything is perfect - the commands inside the script are ran as sudo.... (1 Reply)
Discussion started by: boqsc
1 Replies
LEARN ABOUT DEBIAN
pthread_atfork
PTHREAD_ATFORK(3) Library Functions Manual PTHREAD_ATFORK(3)NAME
pthread_atfork - register handlers to be called at fork(2) time
SYNOPSIS
#include <pthread.h>
int pthread_atfork(void (*prepare)(void), void (*parent)(void), void (*child)(void));
DESCRIPTION
pthread_atfork registers handler functions to be called just before and just after a new process is created with fork(2). The prepare han-
dler will be called from the parent process, just before the new process is created. The parent handler will be called from the parent
process, just before fork(2) returns. The child handler will be called from the child process, just before fork(2) returns.
One or several of the three handlers prepare, parent and child can be given as NULL, meaning that no handler needs to be called at the cor-
responding point.
pthread_atfork can be called several times to install several sets of handlers. At fork(2) time, the prepare handlers are called in LIFO
order (last added with pthread_atfork, first called before fork), while the parent and child handlers are called in FIFO order (first
added, first called).
To understand the purpose of pthread_atfork, recall that fork(2) duplicates the whole memory space, including mutexes in their current
locking state, but only the calling thread: other threads are not running in the child process. The mutexes are not usable after the fork
and must be initialized with pthread_mutex_init in the child process. This is a limitation of the current implementation and might or
might not be present in future versions.
RETURN VALUE
pthread_atfork returns 0 on success and a non-zero error code on error.
ERRORS
ENOMEM insufficient memory available to register the handlers.
AUTHOR
Xavier Leroy <Xavier.Leroy@inria.fr>
SEE ALSO fork(2), pthread_mutex_lock(3), pthread_mutex_unlock(3).
LinuxThreads PTHREAD_ATFORK(3)