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Top Forums Shell Programming and Scripting Not able to understand use exec command Post 302762203 by tokiwinter on Monday 28th of January 2013 08:30:16 AM
Old 01-28-2013
Hi,

This is all expected behaviour.

Also

Code:
$ exec 1>ex

Will overwrite, not append. If you just want to redirect the output of a single run of ls to a file, run

Code:
$ ls -ltr 1>ex

As STDOUT is the default, you don't even need the 1 here.

If you are trying to understand the functionality/purpose of the exec command I'd recommend reading your shell's man page.
 

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DH-EXEC-SUBST(1)						      dh-exec							  DH-EXEC-SUBST(1)

NAME
dh-exec-subst - Debhelper executable file substition scripts SYNOPSIS
#! /usr/bin/dh-exec src/libfoo-*.so.* debian/foo-plugins/usr/lib/foo/${DEB_HOST_MULTIARCH}/ DESCRIPTION
Being a sub-command of dh-exec(1), this program must not be ran directly, but through dh-exec, which automatically runs all available sub-commands if run bare; or explicitly with dh-exec --with=subst. It is a wrapper around the various other substitution helpers, and will pipe the input file through all the available substitution helpers. It is up to these scripts to do the actual work. When a helper fails to expand a variable within its input, it will leave it as-is, so that later in the pipeline it can perhaps be expanded by another program. SCRIPTS
dh-exec-subst-env Substitutes any of the available, exported environment variables into its input. It does not do any kind of filtering: whatever is available in the environment, will be available for substitution, however unsafe that may be. dh-exec-subst-multiarch Attempts to expand any of the variables known to dpkg-architecture(1), mostly useful for multi-arch support. The command will query dpkg-architecture(1) directly, and does not rely on environment variables set (as the called program will prefer already set environment variables anyway). ENVIRONMENT
DH_EXEC_SCRIPTDIR Indicates which directory the command-specific scripts should be sought for. If not specified, scripts will be searched for in /usr/share/dh-exec/. FILES
$DH_EXEC_SCRIPTDIR/dh-exec-subst-* The various scripts for the higher-level program. SEE ALSO
debhelper(1), dh-exec(1) AUTHOR
dh-exec-subst is copyright (C) 2011-2012 by Gergely Nagy <algernon@madhouse-project.org>. 2012-05-03 DH-EXEC-SUBST(1)
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