Reverse the words but keep the order Bash

Question

I have a file with lines. I want to reverse the words, but keep them in same order. For example: "Test this word" Result: "tseT siht drow"

I'm using MAC, so awk doesn't seem to work. What I got for now

input=FILE_PATH
while IFS= read -r line || [[ -n $line ]]
do
    echo $line | rev
done < "$input"

Answer 1

Here is a solution that completely avoids awk

#!/bin/bash

input=./data
while read -r line ; do
    for word in  $line ; do
        output=`echo $word | rev`
        printf "%s " $output
    done
    printf "\n"
done < "$input"

Answer 2

如果xargs在Mac上可以使用：

echo "Test this word"  | xargs -n 1 | rev | xargs

Answer 3

Using rev and awk

Consider this as the sample input file:

$ cat file
Test this word
Keep the order

Try:

$ rev <file | awk '{for (i=NF; i>=2; i--) printf "%s%s",$i,OFS; print $1}'
tseT siht drow
peeK eht redro

(This uses awk but, because it uses no advanced awk features, it should work on MacOS.)

Using in a script

If you need to put the above in a script, then create a file like:

$ cat script
#!/bin/bash
input="/Users/Anastasiia/Desktop/Tasks/test.txt"
rev <"$input" | awk '{for (i=NF; i>=2; i--) printf "%s%s",$i,OFS; print $1}'

And, run the file:

$ bash script
tseT siht drow
peeK eht redro

Using bash

while read -a arr
do
   x=" "
   for ((i=0; i<${#arr}; i++))
   do
      ((i == ${#arr}-1)) && x=$'\n'
      printf "%s%s" $(rev <<<"${arr[i]}") "$x"
   done
done <file

Applying the above to our same test file:

$ while read -a arr; do x=" "; for ((i=0; i<${#arr}; i++)); do ((i == ${#arr}-1)) && x=$'\n'; printf "%s%s" $(rev <<<"${arr[i]}") "$x"; done; done <file
tseT siht drow 
peeK eht redro 

Answer 4

Inside your read loop, you can just iterate over the words of your string and pass them to rev

line="Test this word"
for word in "$line"; do
    echo -n " $word" | rev
done
echo  # Add final newline

output

tseT siht drow

Answer 5

You are actually in fairly good shape with bash. You can use string-indexes and string-length and C-style for loops to loop over the characters in each word building a reversed string to output. You can control formatting in a number of ways to handle spaces between words, but a simple flag first=1 is about as easy as anything else. You can do the following with your read,

#!/bin/bash

while read -r line || [[ -n $line ]]; do        ## read line
    first=1                                     ## flag to control space
    a=( $( echo $line ) )                       ## put line in array
    for i in "${a[@]}"; do                      ## for each word
        tmp=                                    ## clear temp
        len=${#i}                               ## get length
        for ((j = 0; j < len; j++)); do         ## loop length times
            tmp="${tmp}${i:$((len-j-1)):1}"     ## add char len - j to tmp
        done
        if [ "$first" -eq '1' ]; then           ## if first word
            printf "$tmp"; first=0;             ## output w/o space
        else
            printf " $tmp"                      ## output w/space
        fi
    done
    echo ""     ## output newline
done

Example Input

$ cat dat/lines2rev.txt
my dog has fleas
the cat has none

Example Use/Output

$ bash revlines.sh <dat/lines2rev.txt
ym god sah saelf
eht tac sah enon

Look things over and let me know if you have questions.