intersting are only the last 10 lines. I try to write to factor, then read, than write again (...) until 0 is given. This wont work, because read(p_stdout[READ], ....) always blocks the programm, waiting for some better waeather are someso. I tried to use fsync() between write and read, but it didnt help. Only fclose() solve the problem, but if p_stdin[WRITE] is closed, i can only iterate the loop one times.
Can someone help me? Thx :-)
Of course, we can help. It's just a matter how much you're willing to pay
More seriously, I think your problem is simply related to the fact that stdout is line buffered. If you switch to unbuffered mode in the child, this may perhaps solve your problem:
Another alternative would be that the factor program fflush each message it writes to stdout.
Besides that, a few comment to your code:
- you may want to use the constant STDIN_FILENO and STDOUT_FILENO defined in <unistd.h> instead of your READ and WRITE constant.
- Once you dup2, you may close the descriptor you have duplicated (p_stdin[READ] and p_stdout[WRITE])
Is there any possibility that a Stream Read and Write queues will interchange messages of any kind. If so what are the different possiblites and under what circumstances ?
Thanks in advance. (4 Replies)
I am programming some data loader of oracle with unix c, when I find new data file, then read it to database and delete it. but one issue, if the file is in process of creating, not been closed yet. I will read zero or part of data content, this will cause problem. I want to know whether some unix... (2 Replies)
Hi Everyone,
Good day.
Scenario:
2 unix servers -- A (SunOS) and B (AIX)
I have an ftp script to sftp 30 files from A to B which happen almost instantaneously i.e 30 sftp's happen at the same time.
Some of these sftp's fail with the following error:
ssh_exchange_identification: Connection... (1 Reply)
Can you help me ?
I want to write a program ,which can open a input file (input.txt) and run as child process ,then write to output file (output.txt).......
char inFile="input.txt";
char outFile="output.txt";
int main(int argc, char **argv)
{
pid_t pid=1;
int no=0; // no. of... (5 Replies)
Hi,
I have file which contains information written in blocks (every block is different). Is it possible to read every block one by one to another file (one block per file).
The input is something like this
<block1>
<empty line>
<block2>
<empty line>
...
...
...
<block25>
<empty... (0 Replies)
Hi
I used this command:
mplayer http://host/axis-cgi/mjpg/video.cgi -user root -passwd root \
-cache 1024 -fps 25.0 -nosound -vc ffh264 \
-demuxer 3 -dumpstream -dumpfile output.avi It's ok but...
Video Playing is very fast! Why? Is it a synch problem?
What parameter I have to use for... (1 Reply)
I'm Unix. I'm looking at "df" on Unix now and below is an example. It's lists the filesystems out in 512-blocks, I need this in 4k blocks. Is there a way to do this in Unix or do I manually convert and how?
So for container 1 there is 7,340,032 in size in 512-blocks. What would the 4k block be... (2 Replies)
Hello,
I have a file like this:
FILE.TXT:
(define argc :: int)
(assert ( > argc 1))
(assert ( = argc 1))
<check>
#
(define c :: float)
(assert ( > c 0))
(assert ( = c 0))
<check>
#
now, i want to separate each block('#' is the delimeter), make them separate files, and then send them as... (5 Replies)
I have a script that takes 2 parameters (say) as mandatory
script1.sh a b
The 3rd parameter can be filename which it should process or it can come through a pipeline stream
The script should work both ways:
script1.sh a b filec
or cat filec | script1.sh a b
How to put logic in the... (1 Reply)
Hello,
Searched for a while and found some "line-to-column" script. My case is similar but with multiple fields each row:
S02 Length Per
S02 7043 3.864
S02 54477 29.89
S02 104841 57.52
S03 Length Per
S03 1150 0.835
S03 1321 0.96
S03 ... (9 Replies)
Discussion started by: yifangt
9 Replies
LEARN ABOUT CENTOS
start_transaction
START TRANSACTION(7) PostgreSQL 9.2.7 Documentation START TRANSACTION(7)NAME
START_TRANSACTION - start a transaction block
SYNOPSIS
START TRANSACTION [ transaction_mode [, ...] ]
where transaction_mode is one of:
ISOLATION LEVEL { SERIALIZABLE | REPEATABLE READ | READ COMMITTED | READ UNCOMMITTED }
READ WRITE | READ ONLY
[ NOT ] DEFERRABLE
DESCRIPTION
This command begins a new transaction block. If the isolation level, read/write mode, or deferrable mode is specified, the new transaction
has those characteristics, as if SET TRANSACTION (SET_TRANSACTION(7)) was executed. This is the same as the BEGIN(7) command.
PARAMETERS
Refer to SET TRANSACTION (SET_TRANSACTION(7)) for information on the meaning of the parameters to this statement.
COMPATIBILITY
In the standard, it is not necessary to issue START TRANSACTION to start a transaction block: any SQL command implicitly begins a block.
PostgreSQL's behavior can be seen as implicitly issuing a COMMIT after each command that does not follow START TRANSACTION (or BEGIN), and
it is therefore often called "autocommit". Other relational database systems might offer an autocommit feature as a convenience.
The DEFERRABLE transaction_mode is a PostgreSQL language extension.
The SQL standard requires commas between successive transaction_modes, but for historical reasons PostgreSQL allows the commas to be
omitted.
See also the compatibility section of SET TRANSACTION (SET_TRANSACTION(7)).
SEE ALSO BEGIN(7), COMMIT(7), ROLLBACK(7), SAVEPOINT(7), SET TRANSACTION (SET_TRANSACTION(7))
PostgreSQL 9.2.7 2014-02-17 START TRANSACTION(7)
01-25-2010
