mjhjmtu

I have the following (MWE) shell script foo:

#!/bin/bash
ARGS=("$@") # all arguments
## => if it exists, we need to drop the argument "-D" here
ls -l $ARGS[@] | sort -fk8 

If foo is called with argument -D (the position in the list of arguments is unknown), how can I remove -D from the list of arguments? I found out that unset ARGS[$#ARGS[@]-1] can drop the last argument, for example, but I'm not sure in which order the arguments are passed (so I first need to know at which place the argument is and then remove it in case it is provided).

The no-frills approach is to simply loop over the positional parameters, collecting all but -D into an array, and then use set -- to update the params:

for param; do 
 [[ ! $param == '-D' ]] && newparams+=("$param")
done
set -- "$newparams[@]" # overwrites the original positional params

With zsh, use the $array:#pattern parameter expansion operator:

$ set foo -D -D bar '' $'anb'
$ printf '<%s>n' "$@:#-D"
<foo>
<bar>
<>
<a
b>

POSIXly:

for i do
 [ "$i" = -D ] || set -- "$@" "$i"
 shift
done
printf '<%s>n' "$@"

BTW, you forgot the quotes, -- and -d:

ls -ld -- "$@"

If you want to sort by modification time, you can just use the -t option, here with -r (reverse) for oldest first:

ls -lrtd -- "$@"

Beware that if $ARGS is an empty array, it will list .. So you can do:

[ "$@" -eq 0 ] || ls -lrtd -- "$@"

To sort reliably based on the hour of the day irrespective of date, with zsh and a ls implementation that supports -U for not sorting:

zmodload zsh/stat # best in ~/.zshrc
bytime() zstat -LA REPLY -F%T +mtime -- $REPLY
ls --full-time -ldU -- .(e'reply=("$@")'o+bytime)

With limited shells like bash, it's very hard to sort files based on arbitrary metadata like that. Again, if you've got access to recent GNU tools, it's slightly easier:

[ "$#" -gt 0 ] && (
 export LC_ALL=C
 printf '%s' "$@" |
 sed -z 's|^-$|./-|' |
 xargs -r0 stat --printf '%yt%n' -- |
 sort -zk2,2 |
 cut -zf 2-
) | xargs -r0 ls -lUd --

Portably (but still using the non-standard ls -U here), it's generally easier to resort to perl, like:

perl -MPOSIX -e '
 exec qwls -ldU --, 
 map $_->[1]
 sort $a->[0] cmp $b->[0]
 map [strftime("%T", localtime((lstat$_)[9])), $_]
 @ARGV' -- "$@"