How can this code construct be optimized to avoid duplicate code (git diff --ignore-space-at-eol -U0)?

while [ ! -z "$(git diff --ignore-space-at-eol -U0)" ]; do
  diff_text=$(git diff --ignore-space-at-eol -U0);
  echo $diff_text
done

In PHP it could be done like this:

while (! $diff_text = "git diff --ignore-space-at-eol -U0") {
  echo $diff_text;
}

We need code so that the diff_text variable is subtracted 1 time.

CodePudding user response：

You can insert multiple instructions inside the while condition block:

while
  diff_text=$(git diff --ignore-space-at-eol -U0)
  [ -n "$diff_text" ]
do
  echo "$diff_text"
done

CodePudding user response：

Use an infinite loop with a break condition to add commands before the comparison that breaks the loop:

while true; do
   i=$(date)
   echo $i
   [[ "$i" =~ "9 " ]] && break
   sleep 1
done 

CodePudding user response：

One option is to use a function that sets the diff_text variable, and returns non-zero if it is empty:

function set_diff_text
{
    diff_text=$(git diff --ignore-space-at-eol -U0)

    [[ -n $diff_text ]] && return 0 || return 1
}

while set_diff_text; do
    printf '%s\n' "$diff_text"
done

Another way to use a function to do it is:

function get_diff_text
{
    local difftxt
    difftxt=$(git diff --ignore-space-at-eol -U0)
    printf '%s\n' "$difftxt"

    [[ -n $difftxt ]] && return 0 || return 1
}

while diff_text=$(get_diff_text); do
    printf '%s\n' "$diff_text"
done

• See the accepted, and excellent, answer to Why is printf better than echo? for an explanation of why I used printf instead of echo to print the git diff output.