RE: [iproute PATCH 4/4] lib: Enable colored output only for TTYs
From: Stephen Hemminger > Sent: 15 August 2018 16:04 ... > > This also disables color sequence when the output is piped to a pager > > such as less which with the -R argument can handle it just fine. > > > > ie., the user needs to remove the color arg when that output is not wanted. > > If you are going to change the color enabling, why not make it compatible > with what ls does? Indeed - otherwise it is very hard to debug the colour escape sequences. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
Re: [iproute PATCH 4/4] lib: Enable colored output only for TTYs
On Wed, 15 Aug 2018 08:40:20 -0600
David Ahern wrote:
> On 8/15/18 3:06 AM, Phil Sutter wrote:
> > Add an additional prerequisite to check_enable_color() to make sure
> > stdout actually points to an open TTY device. Otherwise calls like
> >
> > | ip -color a s >/tmp/foo
> >
> > will print color escape sequences into that file.
> >
> > Signed-off-by: Phil Sutter
> > ---
> > lib/color.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/lib/color.c b/lib/color.c
> > index edf96e5c6ecd7..500ba09682697 100644
> > --- a/lib/color.c
> > +++ b/lib/color.c
> > @@ -3,6 +3,7 @@
> > #include
> > #include
> > #include
> > +#include
> > #include
> > #include
> > #include
> > @@ -79,7 +80,7 @@ void enable_color(void)
> >
> > int check_enable_color(int color, int json)
> > {
> > - if (color && !json) {
> > + if (color && !json && isatty(fileno(stdout))) {
> > enable_color();
> > return 0;
> > }
> >
>
> This also disables color sequence when the output is piped to a pager
> such as less which with the -R argument can handle it just fine.
>
> ie., the user needs to remove the color arg when that output is not wanted.
If you are going to change the color enabling, why not make it compatible
with what ls does?
From man ls(1) (and grep)
--color[=WHEN]
colorize the output; WHEN can be 'always' (default if omitted),
'auto', or 'never'; more info below
...
Using color to distinguish file types is disabled both by default and
with --color=never. With --color=auto, ls emits color codes only when
standard output is connected to a terminal. The LS_COLORS environment
variable can change the settings. Use the dircolors command to set it.
Make -c be same as --color=always to keep compatiablity
Re: [iproute PATCH 4/4] lib: Enable colored output only for TTYs
On 8/15/18 3:06 AM, Phil Sutter wrote:
> Add an additional prerequisite to check_enable_color() to make sure
> stdout actually points to an open TTY device. Otherwise calls like
>
> | ip -color a s >/tmp/foo
>
> will print color escape sequences into that file.
>
> Signed-off-by: Phil Sutter
> ---
> lib/color.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/lib/color.c b/lib/color.c
> index edf96e5c6ecd7..500ba09682697 100644
> --- a/lib/color.c
> +++ b/lib/color.c
> @@ -3,6 +3,7 @@
> #include
> #include
> #include
> +#include
> #include
> #include
> #include
> @@ -79,7 +80,7 @@ void enable_color(void)
>
> int check_enable_color(int color, int json)
> {
> - if (color && !json) {
> + if (color && !json && isatty(fileno(stdout))) {
> enable_color();
> return 0;
> }
>
This also disables color sequence when the output is piped to a pager
such as less which with the -R argument can handle it just fine.
ie., the user needs to remove the color arg when that output is not wanted.
