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Top Forums Shell Programming and Scripting Can someone interpret this -- not sure Post 302419524 by alister on Friday 7th of May 2010 11:58:33 AM
Old 05-07-2010
Quote:
Originally Posted by Straitsfan
I mean a directory with just that more than one word in its name -- say, for example my\ documents/ as opposed to just documents/
It's not more than one word if you quote it. In that case, there is no field splitting done and it will always be one word (word in the bash man page sense) which happens to contain a space.


Quote:
Originally Posted by hergp
In this special case there is no effective difference between "$*" and "$@", because in bash the cd builtin accepts only one argument, the name of the directory you want to change to.
That is absolutely incorrect. If there are multiple arguments passed to a script or function, the double-quoted values "$*" and "$@" will ALWAYS differ. The former will always expand to one string, the latter to multiple strings.

If this function were called with two arguments, for example, it would try to cd into a directory named "$1" (as you pointed out, bash's built-in cd would ignore $2 and any other arguments). However, if the code were using "$*" instead, the bash builtin would be passed a single argument whose value would be "$1 $2". Definitely, not the same.

In this case, what is equivalent is the use "$@" and "$1", since bash's cd will ignore all other arguments.

Regards,
Alister
 

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SHELL-QUOTE(1p) 					User Contributed Perl Documentation					   SHELL-QUOTE(1p)

NAME
shell-quote - quote arguments for safe use, unmodified in a shell command SYNOPSIS
shell-quote [switch]... arg... DESCRIPTION
shell-quote lets you pass arbitrary strings through the shell so that they won't be changed by the shell. This lets you process commands or files with embedded white space or shell globbing characters safely. Here are a few examples. EXAMPLES
ssh preserving args When running a remote command with ssh, ssh doesn't preserve the separate arguments it receives. It just joins them with spaces and passes them to "$SHELL -c". This doesn't work as intended: ssh host touch 'hi there' # fails It creates 2 files, hi and there. Instead, do this: cmd=`shell-quote touch 'hi there'` ssh host "$cmd" This gives you just 1 file, hi there. process find output It's not ordinarily possible to process an arbitrary list of files output by find with a shell script. Anything you put in $IFS to split up the output could legitimately be in a file's name. Here's how you can do it using shell-quote: eval set -- `find -type f -print0 | xargs -0 shell-quote --` debug shell scripts shell-quote is better than echo for debugging shell scripts. debug() { [ -z "$debug" ] || shell-quote "debug:" "$@" } With echo you can't tell the difference between "debug 'foo bar'" and "debug foo bar", but with shell-quote you can. save a command for later shell-quote can be used to build up a shell command to run later. Say you want the user to be able to give you switches for a command you're going to run. If you don't want the switches to be re-evaluated by the shell (which is usually a good idea, else there are things the user can't pass through), you can do something like this: user_switches= while [ $# != 0 ] do case x$1 in x--pass-through) [ $# -gt 1 ] || die "need an argument for $1" user_switches="$user_switches "`shell-quote -- "$2"` shift;; # process other switches esac shift done # later eval "shell-quote some-command $user_switches my args" OPTIONS
--debug Turn debugging on. --help Show the usage message and die. --version Show the version number and exit. AVAILABILITY
The code is licensed under the GNU GPL. Check http://www.argon.org/~roderick/ or CPAN for updated versions. AUTHOR
Roderick Schertler <roderick@argon.org> perl v5.8.4 2005-05-03 SHELL-QUOTE(1p)
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