Date: Fri, 27 Jan 2012 11:50:07 GMT From: Bruce Evans <brde@optusnet.com.au> To: freebsd-bugs@FreeBSD.org Subject: Re: bin/164535: ps(1) truncates command to screen size even when stdout is not a tty Message-ID: <201201271150.q0RBo7Fd035638@freefall.freebsd.org>
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The following reply was made to PR bin/164535; it has been noted by GNATS.
From: Bruce Evans <brde@optusnet.com.au>
To: Marcus Reid <marcus@blazingdot.com>
Cc: freebsd-gnats-submit@freebsd.org, freebsd-bugs@freebsd.org
Subject: Re: bin/164535: ps(1) truncates command to screen size even when
stdout is not a tty
Date: Fri, 27 Jan 2012 22:49:35 +1100 (EST)
On Fri, 27 Jan 2012, Marcus Reid wrote:
>> Description:
> ps(1) truncates long commands to the size of the screen even when stdout is not a terminal. This is counter-intuitive and differs from another implementation I looked at. Output of ps | grep differs depending on how big your terminal window is for example.
>> How-To-Repeat:
> ps aux | grep
> ps auxww | grep
>> Fix:
> Patch included. Tested; behavior remains consistent with docs: COLUMNS variable retains effect, and -w limits to 132 characters still.
>
>
> Patch attached with submission follows:
>
> --- bin/ps/ps.c.orig 2012-01-27 01:24:10.519024952 -0800
> +++ bin/ps/ps.c 2012-01-27 01:24:20.350023629 -0800
> @@ -187,6 +187,8 @@
>
> if ((cols = getenv("COLUMNS")) != NULL && *cols != '\0')
> termwidth = atoi(cols);
> + else if (isatty(STDOUT_FILENO) == 0)
> + termwidth = UNLIMITED;
This change defeats the else clause, which checks all of STDOUT_FILENO,
STDERR_FILENO and STDIN_FILENO and uses the terminal width iff any if
these is a terminal according to the TIOCGWINSZ test for being a
terminal, and otherwise gives a default of 79 columns (not UNLIMITED,
which is only documented for ps -ww and only reachable using that and
via the missing sanity checking for COLUMNS=0).
> else if ((ioctl(STDOUT_FILENO, TIOCGWINSZ, (char *)&ws) == -1 &&
> ioctl(STDERR_FILENO, TIOCGWINSZ, (char *)&ws) == -1 &&
> ioctl(STDIN_FILENO, TIOCGWINSZ, (char *)&ws) == -1) ||
So the correct way to avoid terminalness when outputting to a file
is "ps </dev/null >foo 2>&1". This is too strange for stdin, so
apparently checking all 3 fd's is a feature, precisely to get the
terminal width from somewhere even when stdout and stderr are
redirected to a file. "COLUMNS=0 ps" is an easier way. If this
feature is considered a bug, then remove the checks of STDERR_FILENO
and STDIN_FILENO.
Bruce
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