How to trim whitespace from a Bash variable?

Question

I have a shell script with this code:

var=`hg st -R \"$path\"`
if [ -n \"$var\" ]; then
    echo $var
fi

But the conditional code always ex

Answer 1

Assignments ignore leading and trailing whitespace and as such can be used to trim:

$ var=`echo '   hello'`; echo $var
hello

Answer 2

I found that I needed to add some code from a messy sdiff output in order to clean it up:

sdiff -s column1.txt column2.txt | grep -F '<' | cut -f1 -d"<" > c12diff.txt 
sed -n 1'p' c12diff.txt | sed 's/ *$//g' | tr -d '\n' | tr -d '\t'

This removes the trailing spaces and other invisible characters.

Answer 3

var='   a b c   '
trimmed=$(echo $var)

Answer 4

This will remove all the whitespaces from your String,

 VAR2="${VAR2//[[:space:]]/}"

/ replaces the first occurrence and // all occurrences of whitespaces in the string. I.e. all white spaces get replaced by – nothing

Answer 5

You can delete newlines with tr:

var=`hg st -R "$path" | tr -d '\n'`
if [ -n $var ]; then
    echo $var
done

Answer 6

Removing spaces to one space:

(text) | fmt -su