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Full Discussion: Append stderr
Top Forums Shell Programming and Scripting Append stderr Post 302423161 by canduc17 on Thursday 20th of May 2010 09:23:30 AM
Old 05-20-2010
Thank you so much scottn!
Now my script works as I wanted to and I have definetely better understood bash redirection.

I've reimplemented your last example in a way more similar to my case: instead of producing strings on stdout and stderr with bash, I produce them with a C program, then executed by a script.

Here's the C prog:
Code:
#include <stdio.h>
#include <unistd.h>

int main()
{
    int i;

    for(i=0; i<3; i++)
    {
        fprintf(stdout, "This is message n. %d on the standard output\n", i);
        fprintf(stderr, "This is message n. %d on the standard error\n", i);
        sleep(1);
    }

    return 0;
}

After the compilation, I have executed it with the following script:
Code:
#!/bin/bash

COMMAND="stdoutAndstderr"
OUTLOG="stdout.log"
ERRLOG="stderr.log"

log()
{
    while read LINE; do
        echo "$(date +"%D %T") - ${LINE}" >> ${ERRLOG}
    done
}

$(pwd)/${COMMAND} 2>&1 >> ${OUTLOG} | log

echo "${OUTLOG}:"
cat ${OUTLOG}
echo ""
echo "${ERRLOG}:"
cat ${ERRLOG}

exit 0

And the output is
Code:
 $ ./stdoutAndstderr.sh
stdout.log:
This is message n. 0 on the standard output
This is message n. 1 on the standard output
This is message n. 2 on the standard output

stderr.log:
05/20/10 15:18:52 - This is message n. 0 on the standard error
05/20/10 15:18:53 - This is message n. 1 on the standard error
05/20/10 15:18:54 - This is message n. 2 on the standard error

Hope to be helpful for someone!
 

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LEARN ABOUT V7

systemd-cat

SYSTEMD-CAT(1)							    systemd-cat 						    SYSTEMD-CAT(1)

NAME

       systemd-cat - Connect a pipeline or program's output with the journal

SYNOPSIS

       systemd-cat [OPTIONS...] [COMMAND] [ARGUMENTS...]

       systemd-cat [OPTIONS...]

DESCRIPTION

       systemd-cat may be used to connect the standard input and output of a process to the journal, or as a filter tool in a shell pipeline to
       pass the output the previous pipeline element generates to the journal.

       If no parameter is passed, systemd-cat will write everything it reads from standard input (stdin) to the journal.

       If parameters are passed, they are executed as command line with standard output (stdout) and standard error output (stderr) connected to
       the journal, so that all it writes is stored in the journal.

OPTIONS

       The following options are understood:

       -h, --help
	   Print a short help text and exit.

       --version
	   Print a short version string and exit.

       -t, --identifier=
	   Specify a short string that is used to identify the logging tool. If not specified, no identification string is written to the journal.

       -p, --priority=
	   Specify the default priority level for the logged messages. Pass one of "emerg", "alert", "crit", "err", "warning", "notice", "info",
	   "debug", or a value between 0 and 7 (corresponding to the same named levels). These priority values are the same as defined by
	   syslog(3). Defaults to "info". Note that this simply controls the default, individual lines may be logged with different levels if they
	   are prefixed accordingly. For details, see --level-prefix= below.

       --level-prefix=
	   Controls whether lines read are parsed for syslog priority level prefixes. If enabled (the default), a line prefixed with a priority
	   prefix such as "<5>" is logged at priority 5 ("notice"), and similar for the other priority levels. Takes a boolean argument.

EXIT STATUS

       On success, 0 is returned, a non-zero failure code otherwise.

EXAMPLES

       Example 1. Invoke a program

       This calls /bin/ls with standard output and error connected to the journal:

	   # systemd-cat ls

       Example 2. Usage in a shell pipeline

       This builds a shell pipeline also invoking /bin/ls and writes the output it generates to the journal:

	   # ls | systemd-cat

       Even though the two examples have very similar effects the first is preferable since only one process is running at a time, and both stdout
       and stderr are captured while in the second example, only stdout is captured.

SEE ALSO

       systemd(1), systemctl(1), logger(1)

systemd 237															    SYSTEMD-CAT(1)
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