On Thu, Dec 12, 2002 at 07:14:28PM +1100, BSD Freak wrote:
> Just tried the following and it doesn't seem to work.. any explanations?
>
> %echo first line \\n second line
>
> Output is:
> first line \n second line
echo is both a shell built-in and a standard command. The standard
command doesn't support expanding character escapes like '\n':
% /bin/echo "line one\nline two"
line one\nline two
This is a difference between the BSD echo(1) command and the SYSV
equivalent.
Of the shells bundled with FreeBSD, /bin/sh uses the standard command
version and /bin/tcsh uses a shell built-in that by default has the
same behaviour as /bin/echo:
% echo $SHELL
/bin/tcsh
% echo "line one\nline two"
line one\nline two
However you can set the 'echo_style' shell variable to make the tcsh(1)
built-in behave in the SysV style:
% set echo_style=sysv
% echo "line one\nline two"
line one
line two
Other shells have alternate mechanisms for achieving the same thing,
eg:
bash(1) uses a '-e' flag to the echo command to enable SysV style
bash-2.05b$ echo "line one\nline two"
line one\nline two
bash-2.05b$ echo -e "line one\nline two"
line one
line two
whereas zsh(1) expands character escapes by default:
happy-idiot-talk% echo $ZSH_VERSION
4.0.6
happy-idiot-talk% echo "line one\nline two"
line one
line two
In this case you can use the '-E' flag to make echo behave in the BSD
way:
% echo -E "line one\nline two"
line one\nline two
If you want something that will behave consistently independent of
whatever shell is being used, try the printf(1) command:
% printf "line one\nline two\n"
line one
line two
(Note: no automatic addition of newline after the last character)
Cheers,
Matthew
--
Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks
Savill Way
Marlow
Tel: +44 1628 476614 Bucks., SL7 1TH UK
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