How to echo random amounts of dots mixed with spaces?

问题

I would like bash/terminal command to make it echo

 ...  . . . .  . .  ..  ...... .. . . .

in other words random amounts of dots perhaps 100 dots max, mixed with spaces.

how can this be done via bash script ?

回答1:

Here is a one liner:

max=$((RANDOM%100)); for ((i=0;i<max;i++)); do ((RANDOM%2)) && a="$a." || a="$a "; done; echo "$a"

or in a more readable format:

max=$((RANDOM%100))
for ((i=0;i<max;i++))
do 
    ((RANDOM%2)) && a="$a." || a="$a "
done
echo "$a"

回答2:

If you want the line to be really random, say:

cat /dev/urandom | tr -dc '. ' | fold -w 100 | head -1

For assigning it to a variable, say:

foo=$(cat /dev/urandom | tr -dc '. ' | fold -w 100 | head -1)

A sample output would look like:

  ......   .  . .     .......  .  ...    .....   . ... .  .  .  . .    ..   .... .   .  . .  ... . .

Simply saying:

cat /dev/urandom | tr -dc '. ' | fold -w 100

would produce endless lines of random data that are 100 characters wide until you interrupt.

回答3:

How about this?

#!/bin/bash

for i in {1..100}; do
    even=$(( $RANDOM % 2 ))
    if [ $even -eq 0 ]; then
            printf " ";
    else
            printf "." 
    fi  
done

printf "\n"

Or as asked in the comments:

#!/bin/bash

a=$(
    for i in {1..100}; do
            even=$(( $RANDOM % 2 ))
            if [ $even -eq 0 ]; then
                    printf " ";
            else
                    printf "."
            fi
    done
    printf "\n"
)

echo $a

回答4:

$ x='. '; for i in {1..100}; do printf "${x:$((RANDOM%2)):1}"; done && echo
 . .. ...   .....  .. .   .. .    .. .   .. . ...  .....  . . ..  ... . . .  .. .. ..    .. . .....

That way you can also easily influence the dot-to-space ratio by doing e.g. x='.... ' and using $RANDOM % 5

$ x='.... '; for i in {1..100}; do printf "${x:$((RANDOM%5)):1}"; done && echo
.................. ... ...... . .  ..... .     ........ . ....    ............ ........... .. .  ...

or add other characters to your output

$ x='abc '; for i in {1..100}; do printf "${x:$(($RANDOM%4)):1}"; done && echo
b a ccac  bb aac abbcccab aa   baabb cbbacbacb  cbab b a baccccaa bc  acc  cca ba cacccaaa  cbaba ab

来源：https://stackoverflow.com/questions/18483271/how-to-echo-random-amounts-of-dots-mixed-with-spaces

标签

bash

terminal