for i in `perl -MList::Util=shuffle -e'$,=$";print shuffle<*.txt>'`; do
    ....
done

如果文件名确实有空格但没有嵌入的换行符或反斜杠,请一次读取一行.

perl -MList::Util=shuffle -le'$,=$\;print shuffle<*.txt>' | while read i; do
    ....
done

要在Bash中完全安全,请使用以NUL结尾的字符串.

perl -MList::Util=shuffle -0 -le'$,=$\;print shuffle<*.txt>' |
while read -r -d '' i; do
    ....
done

效率不高,但如果需要,可以在纯Bash中执行此操作. sort -R在内部执行类似的操作.

declare -a a                     # create an integer-indexed associative array
for i in *.txt; do
    j=$RANDOM                    # find an unused slot
    while [[ -n ${a[$j]} ]]; do
        j=$RANDOM
    done
    a[$j]=$i                     # fill that slot
done
for i in "${a[@]}"; do           # iterate in index order (which is random)
    ....
done

或者使用传统的Fisher-Yates shuffle.

a=(*.txt)
for ((i=${#a[*]}; i>1; i--)); do
    j=$[RANDOM%i]
    tmp=${a[$j]}
    a[$j]=${a[$[i-1]]}
    a[$[i-1]]=$tmp
done
for i in "${a[@]}"; do
    ....
done