= Bash Open Questions =
If you want to help with the BashFAQ, you could try to answer one of the following questions. Just answer it, copy it to a new subpage of the BashFAQ page (e.g. [[BashFAQ/101]]), and remove the question here.
 * How can I redirect the output of the script to both standard output and a log file?
  * Duplicating fds is not sufficient, because it duplicates the file descriptor number, not the data.
  * But you can still use {{{tee}}}: {{{exec > >(tee log)}}}
 * Somewhere the content of variables in my script lose whitespace.
  * echo "$var" - quoting.  See BashPitfalls for more.
 * How can I make bash set the xterm title to the command it is currently executing?
  * This can't be done in any straightforward manner because there's no hook in Bash to execute arbitrary code after a user presses Enter but before a command is executed.  The DEBUG trap is triggered after each command, and the PS1 variable is triggered when a prompt is displayed, which is also after the command, rather than before.
  * In bash 4, the DEBUG trap is triggered ''before'' every command, according to `help trap`.  This is a change from bash 3.  So this should be possible in bash 4.  Someone just needs to write it up....
 * How to determine Yesterday's date?
  * date -d'yesterday'  # GNU date (sufficiently new versions)
  * date -d '1 day ago' # GNU date (all versions I have available to test)
  * date -r $(( $(date +%s) - 86400 ))  # OpenBSD date
 * How can I redirect file names using sequential numbers to avoid overwriting existing ones?
  * mv --backup=numbered  # requires GNU mv
 * How can I set the output of a command to a variable without executing a subshell (i.e. $() ) or writing to a file and reading it back?
  * I think this does the job, have not had time to test: http://tldp.org/LDP/abs/html/process-sub.html (see also ProcessSubstitution on this site)
   * Commands in a process substitution ( >(cmd) or <(cmd) ) are definitely run in a subshell (or rather a full-blown background process).  I'm not sure I understand what this question is really asking.  Maybe it's related to [[BashFAQ/084|FAQ 84]].
 * Creating temporary files securely and ''portably'' ([[BashFAQ/062]] has a partial answer)
 * Which shebang — {{{#!/bin/bash}}} or {{{#!/usr/bin/env bash}}} — should be used or in which circumstance?  Is one preferred over the other?