checking a connection still exists?

Thread Tools Search this Thread
Special Forums IP Networking checking a connection still exists?
# 1  
Old 12-13-2007
Bug checking a connection still exists?

Hi I have a bit of c code which I'm trying to use as a relay between apache and a scgi cluster.
Example of problem code is below:

while((n = recv(scgiSock, local_data, MAX_LENGTH, 0)) > 0)
time_now = t2 - t1;
if(time_now > TIMEOUT)
throw 1;
logger("scgi : length := ", 1, n);
logger("sending data: length = ", 1, n);
logger("send ret:= %d", 1, send(receiveSock, local_data, n, 0));
bzero(local_data, MAX_LENGTH + 1);
sum += n;
logger("Receiving data: current sum = ", 1, sum);

I'm encountering a slight but probably easily solveable problem; sometimes apache drops the connection and as a result my program crashes out when trying to send data back on the socket.
Is there any way to check that the socket is still alive before sending data?

# 2  
Old 12-13-2007
Originally Posted by fishman2001
Is there any way to check that the socket is still alive before sending data?
option 1. Use select() to tell you if there is anything to read and when you can write, if the connection drops then you will be told you can read something and will then get the appropriate error returned by "recv", only "send" if select tells you can write.

option 2. install a SIGPIPE signal handler around the send() to catch any raised signal, then restore the handler after the send.
# 3  
Old 12-14-2007
I'm actually using the select() function when I receive information from apache. but I didn't know you could use it to check for sending as well. I'll have to look into that a bit more. would you happend to have any examples of using select in a send situation?

I'm might as well set up the SIGPIPE signal error capture as well. you have any good examples of this?

Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. UNIX for Beginners Questions & Answers

Code for checking if certain no of files exists

Hi, I am writing the shell script in ksh to check certain no of files exists,In my case there are 7 files exist like below Sales1_timstamp.csv Sales2_timstamp.csv Sales3_timstamp.csv Sales4_timstamp.csv Sales5_timstamp.csv Sales7_timstamp.csv Sales7_timstamp.csv Once all the files... (4 Replies)
Discussion started by: SRPR
4 Replies

2. Shell Programming and Scripting

For loop without checking file exists

In several scripts that process files matched by name pattern I needed to add a check for file existence. Just to illustrate let's say I need to process all N??? files: /tmp$ touch N100 N101 /tmp$ l ?10 -rw-rw-r-- 1 moss group 0 Apr 19 11:22 N100 -rw-rw-r-- 1 moss group ... (10 Replies)
Discussion started by: migurus
10 Replies

3. Shell Programming and Scripting

Problem with ssh and checking if file exists

Hi All, I am facing a problem while checking for existence of file over ssh ! Basically, i want to ssh and check if file exists.. If file exists return 1. If file does not exits return 0 (or any value) I am using the below code file_avail=`ssh username@host "if ]; then exit 1;... (10 Replies)
Discussion started by: galaxy_rocky
10 Replies

4. Shell Programming and Scripting

Checking if file exists and unzipping

Hey, I am new to scripting and was wondering what is wrong with this if statement. I want to check if file exists and the if it does to unzip it. I program it as follows if ; then gunzip *_filename.gz fi Thanks in advance! Please use code tags next time for your code and data. (10 Replies)
Discussion started by: mostarac2487
10 Replies

5. Shell Programming and Scripting

Checking whether the file exists under a directory and doing a diff

Hi Everyone, I am writing a shell script for the below needs and would like your suggestions and advices. I have a lot of scripting files(Shell Scripts) under the directory: /home/risk_dev/dev I have another directory which has a lot of shell scripts under the directory: ... (2 Replies)
Discussion started by: filter
2 Replies

6. Shell Programming and Scripting

what is the difference between -f and -e, when checking for file exists

Hi All, what is the difference between -f and -e. Regards, ch33ry (1 Reply)
Discussion started by: ch33ry
1 Replies

7. Shell Programming and Scripting

Checking if file exists

How can I check if a file exists in csh? I know there is "-e $file" but do not know exactly how to use it. I have tried the below but I'm getting "Bad : modifier in $ ( )." foreach f ($AfullnameLst) if (-e $f) then echo "$f: file exists" endif end (6 Replies)
Discussion started by: kristinu
6 Replies

8. Shell Programming and Scripting

checking textfile exists or not in all directories

Hai All, please help me in solving this assignment!!! i need a unix script that has to check the text file exists or not in all directories and sub directories if textfile exists display the directory path else display does not exists!! example: kamal.txt that i want to search if the... (5 Replies)
Discussion started by: G.K.K
5 Replies

9. Shell Programming and Scripting

Checking if a file exists

How can I check if a file exists in shell script. Basically, I want to check if a file Test_msgs has been created today. If it has been then append data to it. Otherwise, create it. I have written the following but it does not work. todaysdate=$(date +%d%m%Y) timenow=$(date +%H%M%S)... (4 Replies)
Discussion started by: gugs
4 Replies

10. Shell Programming and Scripting

Checking the file if it exists

Hi This will be useful who is looking for checking the files in a directory #chmod 777 /cronacle/tools/teradata/opo/bin/ SUBJECT=`echo "File Not Found"` SUBJECT1=`echo "File Found"` cd /cronacle/tools/teradata/opo/bin if ... (3 Replies)
Discussion started by: ksmbabu
3 Replies
Login or Register to Ask a Question