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File operator command

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# 15  
Old 06-13-2015
Thanks, the NOTE explains the difference in md5.
# 16  
Old 06-13-2015
Quote:
Originally Posted by MadeInGermany
Thanks Don and Scrutinizer for pointing that out; the bash man page was not clear for me.
Anyway, I would prefer [[ 0 -ne $# ]] or [ 0 -ne $# ] that would also recognize empty arguments:
Code:
set -- ""
[[ -n $* ]] && echo non-empty arg "$1"
[[ 0 -ne $# ]] && echo arg "$1"

Note that $* expanding to a non-empty list says absolutely nothing about the contents of the 1st positional parameter. With a default IFS, it doesn't even tell you if any of the positional parameters are empty. (In that case, it just tells you that there are two or more positional parameters. With the default IFS, $* expands to a list of positional parameters separated by spaces.) The following, when run with ksh93:
Code:
set -- "" ""
set -xv
unset IFS
echo no IFS
[[ -n $* ]] && echo non-empty arg list \"$*\" || echo empty arg list
echo default IFS
IFS=$' \t\n'
[[ -n $* ]] && echo non-empty arg list \"$*\" || echo empty arg list
echo empty IFS
IFS=
[[ -n $* ]] && echo non-empty arg list \"$*\" || echo empty arg list

produces the output:
Code:
unset IFS
+ unset IFS
echo no IFS
+ echo no IFS
no IFS
[[ -n $* ]] && echo non-empty arg list \"$*\" || echo empty arg list
+ [[ -n ' ' ]]
+ echo non-empty arg list '"' '"'
non-empty arg list " "
echo default IFS
+ echo default IFS
default IFS
IFS=$' \t\n'
+ IFS=$' \t\n'
[[ -n $* ]] && echo non-empty arg list \"$*\" || echo empty arg list
+ [[ -n ' ' ]]
+ echo non-empty arg list '"' '"'
non-empty arg list " "
echo empty IFS
+ echo empty IFS
empty IFS
IFS=
+ IFS=''
[[ -n $* ]] && echo non-empty arg list \"$*\" || echo empty arg list
+ [[ -n '' ]]
+ echo empty arg list
empty arg list

You get similar output with bash, but the trace output is slightly different.
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