How can I join all the lines?

Desired output:

$ echo 'one\ntwo' | tr '\n' ''
onetwo

Actual output:

tr: empty string2

I have also tried paste -sd '' - but get

paste: no delimiters specified

also sed

$ echo 'one\ntwo' | sed 's/\n//'
one
two

CodePudding user response：

tr requires that the second argument have at least one character, so it knows what to translate the characters in the first argument to. If there are less characters in the replacement string than in the match string, the last character of the replacement is used for all the rest. But if the replacement is empty, there's nothing to repeat for the rest.

If you want to delete characters, use tr -d.

echo $'one\ntwo' | tr -d '\n' 

Note also that you have to use $'...' to get the shell to treat \n as a newline. Otherwise it's the literal string \n.

CodePudding user response：

Finally found

$ echo 'one\ntwo' | perl -p -e 's/\n//'
onetwo                                   

there's not even a trailing newline