While writing shell scripts you are using a lot of ‘echo’ but did you think about portability of this simple statement ?
Can you say what will be diplayed, without testing, on your shell, the following tests :
echo \n \c '\n' '\c' "\n" "\c" echo -e \n \c '\n' '\c' "\n" "\c"
I can’t, cause I know that the echo behavior is very implementation dependent, typically in dash, echo -e foo actually print ‘-e foo’ cause the dash’s echo don’t parses any options …
Here is the bug I found on one of my shell scripts, simplified to this 9 bytes shell scripts :
$ cat /tmp/test.sh #!/bin/sh echo "$*" $ /tmp/test.sh '1\n2' 1 2
I’m running Debian Squeeze so my sh is a dash, and the ‘\n’ is interpreted by the dash’s echo … but I don’t want it !
The only portable workaround I found is :
$ cat /tmp/test.sh #!/bin/sh printf "%s\n" "$*" $ /tmp/test.sh '1\n2' 1\n2
Conclusion: Keep a look at your input, if you don’t want backslash-escaped chars to be interpreted and want to be portable, use printf !
You can keep using echo when you have a full control on the input, so the sh Hello World will forever stay :
echo "Hello world"