You can use the following sed commands to trim white space from lines of text:
Trim white space from both sides of a string
echo ' abc ' | sed 's/^ *//;s/ *$//'
Trim white space from the right of a string
echo ' abc ' | sed 's/*//;s/ *$//'
Trim white space from the left of a string
echo ' abc ' | sed 's/^ *//;s/$//'
Trim white space from both ends of every line in a file (keeping a .bak backup)
sed -i.bak 's/^ *//;s/ *$//' file.txt
Trim white space from both ends of every line of every file in the current directory (keeping a .bak backup)
ls -1 | while read line; do cat $line | sed -i.bak 's/^ *//;s/ *$//' $line