When I echo $something >> file.txt, a new line will be append to the file.
What if I want to append without a new line?
4 Answers
That's what echo -n is for .
answered Mar 1, 2012 at 8:28
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4Is there an equivalent for
cat? (e.g. when you have a filesomething.txtrather than a variable$something)– cboettigNov 19, 2013 at 23:05 -
2@cboettig: No. Use a different tool to print everything but the final newline. Nov 19, 2013 at 23:09
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2@cboettig , cat does not add anything to the output by default, so there is no need for a '-n' param for cat. eg, if your file does not have a line-ending in the last line, then your shell prompt will be printed right after the last character of the file and not in a new line– RondoJul 18, 2017 at 22:53
printf is very flexible and more portable than echo. Like the C/Perl/etc implementations, if you do not terminate the format string with \n then no newline is printed:
printf "%s" "$something" >> file.txt
answered Mar 1, 2012 at 14:42
If you are using command's output, you can use xargs in combination with echo
/sbin/ip route|awk '/default/ { print $3 }' | xargs echo -n >> /etc/hosts
tr is another alternative.
If you're using echo as your input you can get away which tr -d '\n'.
This technique also works when piping in output from other commands (with only a single line of output). Moreover, if you don't know whether the files have UNIX or DOS line endings you can use tr -d '\n\r'.
Here are some tests showing that this works.
Newline included:
something='0123456789' ; echo ${something} | wc -c
11
UNIX newline:
something='0123456789' ; echo ${something} | tr -d '\n\r' | wc -c
10
DOS style:
something='0123456789' ; echo ${something} | unix2dos | tr -d '\n\r' | wc -c
10
Tested with BSD tr and GNU tr.
echo $something, its behavior depends on theIFSvariable, and you could end up with disappearing character. You can try the following:var="hello world"; echo $var(two spaces between hello and world) orvar="hello world"; IFS='l'; echo $varorvar="-e hello \\n world"; echo $var. To solve that, put double quotes around the variable like this:echo "$var", or useprintf.