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Full Discussion: standard error to standard out question
Top Forums Shell Programming and Scripting standard error to standard out question Post 302318787 by pludi on Friday 22nd of May 2009 08:46:12 AM
Old 05-22-2009
Even if it would mean changing some of your script, I don't think that it would be too much in relation to gained stability and maintainability, eg if your previous code was
Code:
zfs list | grep fred >/dev/null 2>&1
if [ $? -ne 0 ]...

a change would be as simple as
Code:
if [ -x /path/to/zfs ]
then
    zfs list | grep fred >/dev/null 2>&1
    zfs_found=$?
else
    zfs_found=1
fi
if [ $zfs_found -ne 0 ]...

If, however, you are absolutely sure that there is no other way, at the top of your script put the line
Code:
exec 2>/dev/null

which will redirect all stderr messages to /dev/null (even those that might indicate a serious problem)
Last edited by pludi; 05-22-2009 at 09:57 AM.. Reason: Code example
 

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LEARN ABOUT DEBIAN

zfs-fuse

ZFS-FUSE(8)							  [FIXME: manual]						       ZFS-FUSE(8)

NAME

       zfs-fuse - ZFS filesystem daemon

SYNOPSIS

       zfs-fuse [--pidfile filename] [--no-daemon] [--no-kstat-mount] [--disable-block-cache] [--disable-page-cache] [--fuse-attr-timeout SECONDS]
		[--fuse-entry-timeout SECONDS] [--log-uberblocks] [--max-arc-size MB] [--fuse-mount-options OPT,OPT,OPT...]
		[--min-uberblock-txg MIN] [--stack-size=size] [--enable-xattr] [--help]

DESCRIPTION

       This manual page documents briefly the zfs-fuse command.

       zfs-fuse is a daemon which provides support for the ZFS filesystem, via fuse. Ordinarily this daemon will be invoked from system boot
       scripts.

OPTIONS

       This program follows the usual GNU command line syntax, with long options starting with two dashes (`-'). A summary of options is included
       below. For a complete description, see the Info files.

       -h --help
	   Show summary of options.

       -p filename --pidfile filename
	   Write the daemon's PID to filename after daemonizing. Ignored if --no-daemon is passed.  filename should be a fully-qualified path.

       -n --no-daemon
	   Stay in foreground, don't daemonize.

       --no-kstat-mount
	   Do not mount kstats in /zfs-kstat

       --disable-block-cache
	   Enable direct I/O for disk operations. Completely disables caching reads and writes in the kernel block cache. Breaks mmap() in ZFS
	   datasets too.

       --disable-page-cache
	   Disable the page cache for files residing within ZFS filesystems. Not recommended as it slows down I/O operations considerably.

       -a SECONDS --fuse-attr-timeout SECONDS
	   Sets timeout for caching FUSE attributes in kernel. Defaults to 0.0. Higher values give a 40% performance boost.

       -e SECONDS --fuse-entry-timeout SECONDS
	   Sets timeout for caching FUSE entries in kernel. Defaults to 0.0. Higher values give a 10000% performance boost but cause file
	   permission checking security issues.

       --log-uberblocks
	   Logs uberblocks of any mounted filesystem to syslog

       -m MB --max-arc-size MB
	   Forces the maximum ARC size (in megabytes). Range: 16 to 16384.

       -o OPT... --fuse-mount-options OPT,OPT,OPT...
	   Sets FUSE mount options for all filesystems. Format: comma-separated string of characters.

       -u MIN --min-uberblock-txg MIN
	   Skips uberblocks with a TXG < MIN when mounting any fs

       -v MB --vdev-cache-size MB
	   adjust the size of the vdev cache. Default : 10

       --zfs-prefetch-disable
	   Disable the high level prefetch cache in zfs. This thing can eat up to 150 Mb of ram, maybe more

       --stack-size=size
	   Limit the stack size of threads (in kb). default : no limit (8 Mb for linux)

       -x --enable-xattr
	   Enable support for extended attributes. Not generally recommended because it currently has a significant performance penalty for many
	   small IOPS

       -h --help
	   Show this usage summary.

REMARKS ON PRECEDENCE

       Note that the parameters passed on the command line take precedence over those supplied through /etc/zfs/zfsrc.

BUGS
/CAVEATS
       The path to the configuration file (/etc/zfs/zfsrc) cannot at this time be configured.

       Most existing packages suggest settings can be set at the top of their init script. These get frequently overridden by a (distribution
       specific) /etc/default/zfs-fuse file, if it exists. Be sure to look at these places if you want your changes to options to take effect.

       The /etc/zfs/zfsrc is going to be the recommended approach in the future. So, packagers, please refrain from passing commandline parameters
       within the initscript (except for --pid-file).

SEE ALSO

       zfs (8), zpool (8), zdb(8), zstreamdump(8), /etc/zfs/zfsrc

AUTHOR

       This manual page was written by Bryan Donlan bdonlan@gmail.com for the Debian(TM) system (but may be used by others). Permission is granted
       to copy, distribute and/or modify this document under the terms of the GNU General Public License, Version 2 any later version published by
       the Free Software Foundation, or the Common Development and Distribution License.

       Revised by Seth Heeren zfs-fuse@sehe.nl

       On Debian systems, the complete text of the GNU General Public License can be found in /usr/share/common-licenses/GPL. The text of the
       Common Development and Distribution Licence may be found at /usr/share/doc/zfs-fuse/copyright

COPYRIGHT

       Copyright (C) 2010 Bryan Donlan

[FIXME: source] 						    2010-06-09							       ZFS-FUSE(8)
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