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delete all leading and trailing whitespace from each line in file

Terminal - delete all leading and trailing whitespace from each line in file
sed 's/^\s*//;s/\s*$//' -i file
2010-08-24 05:03:48
User: kaedenn
Functions: sed
0
delete all leading and trailing whitespace from each line in file

Sometimes those files have more than just spaces and tabs around them. Plus, this is just a little shorter.

Alternatives

There are 2 alternatives - vote for the best!

Terminal - Alternatives
sed 's/^[ \t]*//;s/[ \t]*$//' -i file
sed 's/^[ \t]*//;s/[ \t]*$//' < <file> > <file>.out; mv <file>.out <file>

Know a better way?

If you can do better, submit your command here.

What others think

Great ! I was looking for a shell command to trim a string.

Comment by dooblem 225 weeks and 4 days ago

sed -i doesn't *really* edit in place. It will actually write to a new file, thus probably changing the inode. (Use ls -i file before and after to check.) Perhaps more importantly, it will also change the last modified date even if no leading or trailing whitespace was found, and the file data was not actually changed. This is a pain if you want the last modified date to be meaningful! As a workaround you could grep the file first and invoke sed only if grep finds some leading or trailing whitespace.

To avoid these issues, you can script ed:

rmspace () {

ed -s -- "$1"

H

,s/^[[:space:]]\+//

w

EOF

ed -s -- "$1"

H

,s/[[:space:]]\+$//

w

EOF

}

Unfortunately, this solution is not ideal, either! As the ed man page says of the "s" command: "It is an error if no substitutions are performed on any of the addressed lines." So the obvious solution of placing both "s" commands in the same ed invocation fails -- if there is no leading whitespace, ed bombs out and never gets to removing the trailing whitespace. But at least ed doesn't change the last modified date unless it actually updates the file data.

Can anyone see a way to do this with one ed invocation?

Comment by quintic 225 weeks and 3 days ago

Your point of view

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