This depends on the shell. ksh can smash through that wall by moving the "tail -15" to a co-process. I don't know that cleartool command so I'll use "cat /etc/passwd" for my example:
Hi,
I want to find the exit status of the last executed command in C Shell.
Tried $? but getting the error Variable syntax...$? does not seem to work in C shell..
is there any other command in C shell to find the exit status of last command?
Thanks in advance,
raju (1 Reply)
I am executing a find command in my script i.e
find $2 -type f -name '*.gif' -mtime +$1 -exec rm {} \;
how do i check that this command is executed properly.. i would lke t trap the errror and display my error message
kinly help.. this is an urgent issue. (1 Reply)
Hi to everyone.
How can I get the exit status from a remote command executed with rexec? :eek:
machine A has RedHat Linux 9 and the remote machine B has SCO UNIX.
Code:
rexec -l user -p password host sh /u/files/scripts/seq_cal.sh 2006 08
I want the exit status returned by... (1 Reply)
I have a question about how to get the exit code of the first command when it appears in a pipe-lined command.
For example, I have the following script:
grep abc dddd | tee -a log
if ]
then
echo "ERROR!"
fi
In the above script, ] is supposed to test the exit code of "grep abc... (3 Replies)
Hi All,
I am using the following code to move files from one folder to another on the remote server:
ssh username@server <<EOF
cd source_dir
find . -type f -name "*.txt" |xargs -n1000 -i{} mv {} dest_dir
if
then send mail indicating error
otherwise
echo "success"
fi
EOF
... (1 Reply)
I have noticed that on version 11.23 I get exit status 236 from the
following command:
logins -oxl root ; echo $?
> 236
However on 11.31 I get the expected code 0
logins -oxl root ; echo $?
> 0
The output is correct for both versions and contains no error data.
Can anyone explain... (2 Replies)
Hi,
Want to log the output of command & check the exit status to find whether it succeeded or failed.
> ls abc
ls: abc: No such file or directory
> echo $?
1
> ls abc 2>&1 | tee log
ls: abc: No such file or directory
> echo $?
0
Tee commands changes my exit status to be always... (7 Replies)
Guys, I have a problem :confused: and I need some help:
I've to process many huge zip files.
I'd code an application that receive the data from a pipe, so I can simple unzip the data and send it (via pipe) to my app.
Something like that:
gzip -dc <file> | app
The problem is: How can I... (7 Replies)
Hello All,
I am trying to capture the exit status of find command and want to delete the files only when it is successful. But it is always returning me as success even if the pattern of that file doesn't exist in the current directory. please help, checked manual page but couldn't able to figure... (6 Replies)
Hi All,
I am doing an export and import (datapump) of 4 schema. I know we can do an export of 4 schema in one command. But just want to know how to check the exit status if i do the export/import of 4 schema in different commands in background. Please suggest.
Thanks,
Mani (1 Reply)
Discussion started by: pvmanikandan
1 Replies
LEARN ABOUT CENTOS
pipe
PIPE(2) Linux Programmer's Manual PIPE(2)NAME
pipe, pipe2 - create pipe
SYNOPSIS
#include <unistd.h>
int pipe(int pipefd[2]);
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <fcntl.h> /* Obtain O_* constant definitions */
#include <unistd.h>
int pipe2(int pipefd[2], int flags);
DESCRIPTION
pipe() creates a pipe, a unidirectional data channel that can be used for interprocess communication. The array pipefd is used to return
two file descriptors referring to the ends of the pipe. pipefd[0] refers to the read end of the pipe. pipefd[1] refers to the write end
of the pipe. Data written to the write end of the pipe is buffered by the kernel until it is read from the read end of the pipe. For fur-
ther details, see pipe(7).
If flags is 0, then pipe2() is the same as pipe(). The following values can be bitwise ORed in flags to obtain different behavior:
O_NONBLOCK Set the O_NONBLOCK file status flag on the two new open file descriptions. Using this flag saves extra calls to fcntl(2) to
achieve the same result.
O_CLOEXEC Set the close-on-exec (FD_CLOEXEC) flag on the two new file descriptors. See the description of the same flag in open(2) for
reasons why this may be useful.
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is set appropriately.
ERRORS
EFAULT pipefd is not valid.
EINVAL (pipe2()) Invalid value in flags.
EMFILE Too many file descriptors are in use by the process.
ENFILE The system limit on the total number of open files has been reached.
VERSIONS
pipe2() was added to Linux in version 2.6.27; glibc support is available starting with version 2.9.
CONFORMING TO
pipe(): POSIX.1-2001.
pipe2() is Linux-specific.
EXAMPLE
The following program creates a pipe, and then fork(2)s to create a child process; the child inherits a duplicate set of file descriptors
that refer to the same pipe. After the fork(2), each process closes the descriptors that it doesn't need for the pipe (see pipe(7)). The
parent then writes the string contained in the program's command-line argument to the pipe, and the child reads this string a byte at a
time from the pipe and echoes it on standard output.
#include <sys/wait.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
int
main(int argc, char *argv[])
{
int pipefd[2];
pid_t cpid;
char buf;
if (argc != 2) {
fprintf(stderr, "Usage: %s <string>
", argv[0]);
exit(EXIT_FAILURE);
}
if (pipe(pipefd) == -1) {
perror("pipe");
exit(EXIT_FAILURE);
}
cpid = fork();
if (cpid == -1) {
perror("fork");
exit(EXIT_FAILURE);
}
if (cpid == 0) { /* Child reads from pipe */
close(pipefd[1]); /* Close unused write end */
while (read(pipefd[0], &buf, 1) > 0)
write(STDOUT_FILENO, &buf, 1);
write(STDOUT_FILENO, "
", 1);
close(pipefd[0]);
_exit(EXIT_SUCCESS);
} else { /* Parent writes argv[1] to pipe */
close(pipefd[0]); /* Close unused read end */
write(pipefd[1], argv[1], strlen(argv[1]));
close(pipefd[1]); /* Reader will see EOF */
wait(NULL); /* Wait for child */
exit(EXIT_SUCCESS);
}
}
SEE ALSO fork(2), read(2), socketpair(2), write(2), popen(3), pipe(7)COLOPHON
This page is part of release 3.53 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
Linux 2012-02-14 PIPE(2)