I have some files that I'd like to delete the last newline if it is the last character in a file. od -c shows me that the command I run does write the file with a trailing new line:
0013600 n t > \n
I've tried a few tricks with sed but the best I could think of isn't doing the trick:
sed -e '$s/\(.*\)\n$/\1/' abc
Any ideas how to do this?
This is a good solution if you need it to work with pipes/redirection instead of reading/output from or to a file. This works with single or multiple lines. It works whether there is a trailing newline or not.
# with trailing newline
echo -en 'foo\nbar\n' | sed '$s/$//' | head -c -1
# still works without trailing newline
echo -en 'foo\nbar' | sed '$s/$//' | head -c -1
# read from a file
sed '$s/$//' myfile.txt | head -c -1
Details:
head -c -1 truncates the last character of the string, regardless of what the character is. So if the string does not end with a newline, then you would be losing a character.sed '$s/$//' . The first $ means only apply the command to the last line. s/$// means substitute the "end of the line" with "nothing", which is basically doing nothing. But it has a side effect of adding a trailing newline is there isn't one.Note: Mac's default head does not support the -c option. You can do brew install coreutils and use ghead instead.
Yet another answer FTR (and my favourite!): echo/cat the thing you want to strip and capture the output through backticks. The final newline will be stripped. For example:
# Sadly, outputs newline, and we have to feed the newline to sed to be portable
echo thingy | sed -e 's/thing/sill/'
# No newline! Happy.
out=`echo thingy | sed -e 's/thing/sill/'`
printf %s "$out"
# Similarly for files:
file=`cat file_ending_in_newline`
printf %s "$file" > file_no_newline
Here's a simple solution that uses sed.
Your versions of sed needs to support the -z option.
-z, --null-data
separate lines by NUL characters
It can either be used in a pipe or used to edit the file in place with the -i option
sed -ze 's/\n$//' file