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Full Discussion: How to set font color for STDIN,STDOUT and STDERR?
Top Forums UNIX for Advanced & Expert Users How to set font color for STDIN,STDOUT and STDERR? Post 302542402 by Corona688 on Wednesday 27th of July 2011 12:27:16 PM
Old 07-27-2011
The terminal can't tell what's printing to standard output vs standard error -- they both go to literally the same file. You could intercept standard error with a fifo and process it...
Code:
#!/bin/bash

# On exit, close stderr and delete the fifo so we don't leave dangling background processes.
trap "exec 2<&- ; rm ~/.tmpfifo" EXIT

rm -f ~/.tmpfifo

mkfifo ~/.tmpfifo
# Create a subshell that reads from fifo, writes to stderr.
# it gets its own copy of stderr, so redirecting stderr later won't change this.
(       while read LINE
        do
                printf "\x1b[01;31m%s\x1b[01;m\n" "$LINE"
        done < ~/.tmpfifo ) &

exec 2>~/.tmpfifo

# Thing that should print standard error in red
touch /

Code:
$ ./errfilter.sh
touch: setting times of `/': Permission denied
$

This only works for scripts, not for interactive terminals, because bash frequently uses stderr for its own things when in interactive mode.

---------- Post updated at 10:27 AM ---------- Previous update was at 10:11 AM ----------

Actually, here's a way that'll work in interactive mode:

Code:
trap "exec 5>~/.tmpfifo-$$ ; rm -f ~/.tmpfifo-$$ ; exec 5<&-" EXIT

mkfifo ~/.tmpfifo-$$

(       while [ -e ~/.tmpfifo-$$ ]
        do
                while read LINE
                do
                        printf "\x1b[01;31m%s\x1b[01;m\n" "$LINE"
                done < ~/.tmpfifo-$$ >&2
        done
 ) &

function err
{
        "$@" 2>/.tmpfifo-$$
}

Do this in your shell:
Code:
$ source errfilter.sh
$ err touch /
touch: setting times of `/': Permission denied
$

and any commands you run with err will have stderr color-coded.
This User Gave Thanks to Corona688 For This Post:
ungalnanban
 

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LEARN ABOUT CENTOS

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 STDOUT and STDERR of a process with 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
	   Prints a short help text and exits.

       --version
	   Prints a short version string and exits.

       -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 STDOUT/STDERR 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 208															    SYSTEMD-CAT(1)
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