Delete empty lines and trim surrounding spaces in Bash

Question

This command removes empty lines:

sed -e '/^$/d' file 

But, how do I remove spaces from beginning and end of each non-empty line?

Answer 1

$ sed 's/^ *//; s/ *$//; /^$/d' file.txt  `s/^ *//`  => left trim `s/ *$//`  => right trim `/^$/d`    => remove empty line 

Answer 2

Even more simple method using awk.

awk 'NF { $1=$1; print }' file 

NF selects non-blank lines, and $1=$1 trims leading and trailing spaces (with the side effect of squeezing sequences of spaces in the middle of the line).