diff mbox series

[BlueZ] monitor: Add option to set fallback width

Message ID 20210226181158.6538-1-sonnysasaka@chromium.org (mailing list archive)
State New, archived
Headers show
Series [BlueZ] monitor: Add option to set fallback width | expand

Commit Message

Sonny Sasaka Feb. 26, 2021, 6:11 p.m. UTC
Sometimes we want to be able to pipe the output of btmon to a
non-terminal device. The current fallback width is usually not long
enough so this patch adds an option to specify the column width. This is
especially needed for text logs from bluetoothd.

Reviewed-by: Daniel Winkler <danielwinkler@google.com>

---
 monitor/control.c |  4 ++--
 monitor/control.h |  2 +-
 monitor/display.c |  8 ++++++--
 monitor/display.h |  2 +-
 monitor/main.c    | 10 ++++++++--
 5 files changed, 18 insertions(+), 8 deletions(-)

Comments

bluez.test.bot@gmail.com Feb. 26, 2021, 6:39 p.m. UTC | #1
This is automated email and please do not reply to this email!

Dear submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
This is a CI test results with your patch series:
PW Link:https://patchwork.kernel.org/project/bluetooth/list/?series=439141

---Test result---

##############################
Test: CheckPatch - FAIL
Output:
monitor: Add option to set fallback width
ERROR:INITIALISED_STATIC: do not initialise statics to 0
#56: FILE: monitor/display.c:31:
+static int output_width = 0;

- total: 1 errors, 0 warnings, 107 lines checked

NOTE: For some of the reported defects, checkpatch may be able to
      mechanically convert to the typical style using --fix or --fix-inplace.

"[PATCH] monitor: Add option to set fallback width" has style problems, please review.

NOTE: Ignored message types: COMMIT_MESSAGE COMPLEX_MACRO CONST_STRUCT FILE_PATH_CHANGES MISSING_SIGN_OFF PREFER_PACKED SPLIT_STRING SSCANF_TO_KSTRTO

NOTE: If any of the errors are false positives, please report
      them to the maintainer, see CHECKPATCH in MAINTAINERS.


##############################
Test: CheckGitLint - PASS

##############################
Test: CheckBuild - PASS

##############################
Test: MakeCheck - PASS



---
Regards,
Linux Bluetooth
Marcel Holtmann Feb. 26, 2021, 8:09 p.m. UTC | #2
Hi Sonny,

> Sometimes we want to be able to pipe the output of btmon to a
> non-terminal device. The current fallback width is usually not long
> enough so this patch adds an option to specify the column width. This is
> especially needed for text logs from bluetoothd.
> 
> Reviewed-by: Daniel Winkler <danielwinkler@google.com>
> 
> ---
> monitor/control.c |  4 ++--
> monitor/control.h |  2 +-
> monitor/display.c |  8 ++++++--
> monitor/display.h |  2 +-
> monitor/main.c    | 10 ++++++++--
> 5 files changed, 18 insertions(+), 8 deletions(-)
> 
> diff --git a/monitor/control.c b/monitor/control.c
> index d1ba97d37..00001bf1e 100644
> --- a/monitor/control.c
> +++ b/monitor/control.c
> @@ -1474,7 +1474,7 @@ bool control_writer(const char *path)
> 	return !!btsnoop_file;
> }
> 
> -void control_reader(const char *path, bool pager)
> +void control_reader(const char *path, bool pager, int column)
> {
> 	unsigned char buf[BTSNOOP_MAX_PACKET_SIZE];
> 	uint16_t pktlen;
> @@ -1500,7 +1500,7 @@ void control_reader(const char *path, bool pager)
> 	}
> 
> 	if (pager)
> -		open_pager();
> +		open_pager(column);
> 
> 	switch (format) {
> 	case BTSNOOP_FORMAT_HCI:
> diff --git a/monitor/control.h b/monitor/control.h
> index 29616c4f1..ad16358b1 100644
> --- a/monitor/control.h
> +++ b/monitor/control.h
> @@ -12,7 +12,7 @@
> #include <stdint.h>
> 
> bool control_writer(const char *path);
> -void control_reader(const char *path, bool pager);
> +void control_reader(const char *path, bool pager, int column);
> void control_server(const char *path);
> int control_tty(const char *path, unsigned int speed);
> int control_rtt(char *jlink, char *rtt);
> diff --git a/monitor/display.c b/monitor/display.c
> index b11b71d5d..598db8080 100644
> --- a/monitor/display.c
> +++ b/monitor/display.c
> @@ -28,6 +28,7 @@
> #include "display.h"
> 
> static pid_t pager_pid = 0;
> +static int output_width = 0;

why not set this to FALLBACK_TERMINAL_WIDTH?

> bool use_color(void)
> {
> @@ -48,7 +49,8 @@ int num_columns(void)
> 
> 		if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) < 0 ||
> 								ws.ws_col == 0)
> -			cached_num_columns = FALLBACK_TERMINAL_WIDTH;
> +			cached_num_columns = output_width > 0 ?
> +				output_width : FALLBACK_TERMINAL_WIDTH;
> 		else
> 			cached_num_columns = ws.ws_col;
> 	}
> @@ -81,12 +83,14 @@ static void wait_for_terminate(pid_t pid)
> 	}
> }
> 
> -void open_pager(void)
> +void open_pager(int column)
> {
> 	const char *pager;
> 	pid_t parent_pid;
> 	int fd[2];
> 
> +	output_width = column;
> +
> 	if (pager_pid > 0)
> 		return;
> 
> diff --git a/monitor/display.h b/monitor/display.h
> index f3a614b81..70734d590 100644
> --- a/monitor/display.h
> +++ b/monitor/display.h
> @@ -75,5 +75,5 @@ static inline uint64_t print_bitfield(int indent, uint64_t val,
> 
> int num_columns(void);
> 
> -void open_pager(void);
> +void open_pager(int column);
> void close_pager(void);
> diff --git a/monitor/main.c b/monitor/main.c
> index 0f5eb4a3b..5996eed40 100644
> --- a/monitor/main.c
> +++ b/monitor/main.c
> @@ -67,6 +67,7 @@ static void usage(void)
> 		"\t                       Read data from RTT\n"
> 		"\t-R  --rtt [<address>],[<area>],[<name>]\n"
> 		"\t                       RTT control block parameters\n"
> +		"\t-c, --column [width]   Output width if not a terminal\n"

I think we should be using uppercase C.

> 		"\t-h, --help             Show help options\n");
> }
> 
> @@ -90,6 +91,7 @@ static const struct option main_options[] = {
> 	{ "no-pager",  no_argument,       NULL, 'P' },
> 	{ "jlink",     required_argument, NULL, 'J' },
> 	{ "rtt",       required_argument, NULL, 'R' },
> +	{ "column",    required_argument, NULL, 'c' },
> 	{ "todo",      no_argument,       NULL, '#' },
> 	{ "version",   no_argument,       NULL, 'v' },
> 	{ "help",      no_argument,       NULL, 'h' },
> @@ -110,6 +112,7 @@ int main(int argc, char *argv[])
> 	const char *str;
> 	char *jlink = NULL;
> 	char *rtt = NULL;
> +	int column = 0;
> 	int exit_status;
> 
> 	mainloop_init();
> @@ -121,7 +124,7 @@ int main(int argc, char *argv[])
> 		struct sockaddr_un addr;
> 
> 		opt = getopt_long(argc, argv,
> -					"r:w:a:s:p:i:d:B:V:MNtTSAE:PJ:R:vh",
> +					"r:w:a:s:p:i:d:B:V:MNtTSAE:PJ:R:vhc:",

Please don’t put this at the end. The vh is at the end on purpose.

> 					main_options, NULL);
> 		if (opt < 0)
> 			break;
> @@ -205,6 +208,9 @@ int main(int argc, char *argv[])
> 		case 'R':
> 			rtt = optarg;
> 			break;
> +		case 'c':
> +			column = atoi(optarg);
> +			break;
> 		case '#':
> 			packet_todo();
> 			lmp_todo();
> @@ -245,7 +251,7 @@ int main(int argc, char *argv[])
> 		if (ellisys_server)
> 			ellisys_enable(ellisys_server, ellisys_port);
> 
> -		control_reader(reader_path, use_pager);
> +		control_reader(reader_path, use_pager, column);

I prefer that we use a bit more descriptive variable names here. So either num_columns or pager_width or something like that.

> 		return EXIT_SUCCESS;
> 	}

Regards

Marcel
Sonny Sasaka Feb. 26, 2021, 8:50 p.m. UTC | #3
Hi Marcel,

I have addressed your comments in v2. Please take another look. Thanks!

On Fri, Feb 26, 2021 at 12:09 PM Marcel Holtmann <marcel@holtmann.org> wrote:
>
> Hi Sonny,
>
> > Sometimes we want to be able to pipe the output of btmon to a
> > non-terminal device. The current fallback width is usually not long
> > enough so this patch adds an option to specify the column width. This is
> > especially needed for text logs from bluetoothd.
> >
> > Reviewed-by: Daniel Winkler <danielwinkler@google.com>
> >
> > ---
> > monitor/control.c |  4 ++--
> > monitor/control.h |  2 +-
> > monitor/display.c |  8 ++++++--
> > monitor/display.h |  2 +-
> > monitor/main.c    | 10 ++++++++--
> > 5 files changed, 18 insertions(+), 8 deletions(-)
> >
> > diff --git a/monitor/control.c b/monitor/control.c
> > index d1ba97d37..00001bf1e 100644
> > --- a/monitor/control.c
> > +++ b/monitor/control.c
> > @@ -1474,7 +1474,7 @@ bool control_writer(const char *path)
> >       return !!btsnoop_file;
> > }
> >
> > -void control_reader(const char *path, bool pager)
> > +void control_reader(const char *path, bool pager, int column)
> > {
> >       unsigned char buf[BTSNOOP_MAX_PACKET_SIZE];
> >       uint16_t pktlen;
> > @@ -1500,7 +1500,7 @@ void control_reader(const char *path, bool pager)
> >       }
> >
> >       if (pager)
> > -             open_pager();
> > +             open_pager(column);
> >
> >       switch (format) {
> >       case BTSNOOP_FORMAT_HCI:
> > diff --git a/monitor/control.h b/monitor/control.h
> > index 29616c4f1..ad16358b1 100644
> > --- a/monitor/control.h
> > +++ b/monitor/control.h
> > @@ -12,7 +12,7 @@
> > #include <stdint.h>
> >
> > bool control_writer(const char *path);
> > -void control_reader(const char *path, bool pager);
> > +void control_reader(const char *path, bool pager, int column);
> > void control_server(const char *path);
> > int control_tty(const char *path, unsigned int speed);
> > int control_rtt(char *jlink, char *rtt);
> > diff --git a/monitor/display.c b/monitor/display.c
> > index b11b71d5d..598db8080 100644
> > --- a/monitor/display.c
> > +++ b/monitor/display.c
> > @@ -28,6 +28,7 @@
> > #include "display.h"
> >
> > static pid_t pager_pid = 0;
> > +static int output_width = 0;
>
> why not set this to FALLBACK_TERMINAL_WIDTH?
>
> > bool use_color(void)
> > {
> > @@ -48,7 +49,8 @@ int num_columns(void)
> >
> >               if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) < 0 ||
> >                                                               ws.ws_col == 0)
> > -                     cached_num_columns = FALLBACK_TERMINAL_WIDTH;
> > +                     cached_num_columns = output_width > 0 ?
> > +                             output_width : FALLBACK_TERMINAL_WIDTH;
> >               else
> >                       cached_num_columns = ws.ws_col;
> >       }
> > @@ -81,12 +83,14 @@ static void wait_for_terminate(pid_t pid)
> >       }
> > }
> >
> > -void open_pager(void)
> > +void open_pager(int column)
> > {
> >       const char *pager;
> >       pid_t parent_pid;
> >       int fd[2];
> >
> > +     output_width = column;
> > +
> >       if (pager_pid > 0)
> >               return;
> >
> > diff --git a/monitor/display.h b/monitor/display.h
> > index f3a614b81..70734d590 100644
> > --- a/monitor/display.h
> > +++ b/monitor/display.h
> > @@ -75,5 +75,5 @@ static inline uint64_t print_bitfield(int indent, uint64_t val,
> >
> > int num_columns(void);
> >
> > -void open_pager(void);
> > +void open_pager(int column);
> > void close_pager(void);
> > diff --git a/monitor/main.c b/monitor/main.c
> > index 0f5eb4a3b..5996eed40 100644
> > --- a/monitor/main.c
> > +++ b/monitor/main.c
> > @@ -67,6 +67,7 @@ static void usage(void)
> >               "\t                       Read data from RTT\n"
> >               "\t-R  --rtt [<address>],[<area>],[<name>]\n"
> >               "\t                       RTT control block parameters\n"
> > +             "\t-c, --column [width]   Output width if not a terminal\n"
>
> I think we should be using uppercase C.
>
> >               "\t-h, --help             Show help options\n");
> > }
> >
> > @@ -90,6 +91,7 @@ static const struct option main_options[] = {
> >       { "no-pager",  no_argument,       NULL, 'P' },
> >       { "jlink",     required_argument, NULL, 'J' },
> >       { "rtt",       required_argument, NULL, 'R' },
> > +     { "column",    required_argument, NULL, 'c' },
> >       { "todo",      no_argument,       NULL, '#' },
> >       { "version",   no_argument,       NULL, 'v' },
> >       { "help",      no_argument,       NULL, 'h' },
> > @@ -110,6 +112,7 @@ int main(int argc, char *argv[])
> >       const char *str;
> >       char *jlink = NULL;
> >       char *rtt = NULL;
> > +     int column = 0;
> >       int exit_status;
> >
> >       mainloop_init();
> > @@ -121,7 +124,7 @@ int main(int argc, char *argv[])
> >               struct sockaddr_un addr;
> >
> >               opt = getopt_long(argc, argv,
> > -                                     "r:w:a:s:p:i:d:B:V:MNtTSAE:PJ:R:vh",
> > +                                     "r:w:a:s:p:i:d:B:V:MNtTSAE:PJ:R:vhc:",
>
> Please don’t put this at the end. The vh is at the end on purpose.
>
> >                                       main_options, NULL);
> >               if (opt < 0)
> >                       break;
> > @@ -205,6 +208,9 @@ int main(int argc, char *argv[])
> >               case 'R':
> >                       rtt = optarg;
> >                       break;
> > +             case 'c':
> > +                     column = atoi(optarg);
> > +                     break;
> >               case '#':
> >                       packet_todo();
> >                       lmp_todo();
> > @@ -245,7 +251,7 @@ int main(int argc, char *argv[])
> >               if (ellisys_server)
> >                       ellisys_enable(ellisys_server, ellisys_port);
> >
> > -             control_reader(reader_path, use_pager);
> > +             control_reader(reader_path, use_pager, column);
>
> I prefer that we use a bit more descriptive variable names here. So either num_columns or pager_width or something like that.
>
> >               return EXIT_SUCCESS;
> >       }
>
> Regards
>
> Marcel
>
Sonny Sasaka Feb. 26, 2021, 8:53 p.m. UTC | #4
Hi Marcel,

I missed one of your comments in v2. Please take a look at v3 instead. Thanks!

On Fri, Feb 26, 2021 at 12:50 PM Sonny Sasaka <sonnysasaka@chromium.org> wrote:
>
> Hi Marcel,
>
> I have addressed your comments in v2. Please take another look. Thanks!
>
> On Fri, Feb 26, 2021 at 12:09 PM Marcel Holtmann <marcel@holtmann.org> wrote:
> >
> > Hi Sonny,
> >
> > > Sometimes we want to be able to pipe the output of btmon to a
> > > non-terminal device. The current fallback width is usually not long
> > > enough so this patch adds an option to specify the column width. This is
> > > especially needed for text logs from bluetoothd.
> > >
> > > Reviewed-by: Daniel Winkler <danielwinkler@google.com>
> > >
> > > ---
> > > monitor/control.c |  4 ++--
> > > monitor/control.h |  2 +-
> > > monitor/display.c |  8 ++++++--
> > > monitor/display.h |  2 +-
> > > monitor/main.c    | 10 ++++++++--
> > > 5 files changed, 18 insertions(+), 8 deletions(-)
> > >
> > > diff --git a/monitor/control.c b/monitor/control.c
> > > index d1ba97d37..00001bf1e 100644
> > > --- a/monitor/control.c
> > > +++ b/monitor/control.c
> > > @@ -1474,7 +1474,7 @@ bool control_writer(const char *path)
> > >       return !!btsnoop_file;
> > > }
> > >
> > > -void control_reader(const char *path, bool pager)
> > > +void control_reader(const char *path, bool pager, int column)
> > > {
> > >       unsigned char buf[BTSNOOP_MAX_PACKET_SIZE];
> > >       uint16_t pktlen;
> > > @@ -1500,7 +1500,7 @@ void control_reader(const char *path, bool pager)
> > >       }
> > >
> > >       if (pager)
> > > -             open_pager();
> > > +             open_pager(column);
> > >
> > >       switch (format) {
> > >       case BTSNOOP_FORMAT_HCI:
> > > diff --git a/monitor/control.h b/monitor/control.h
> > > index 29616c4f1..ad16358b1 100644
> > > --- a/monitor/control.h
> > > +++ b/monitor/control.h
> > > @@ -12,7 +12,7 @@
> > > #include <stdint.h>
> > >
> > > bool control_writer(const char *path);
> > > -void control_reader(const char *path, bool pager);
> > > +void control_reader(const char *path, bool pager, int column);
> > > void control_server(const char *path);
> > > int control_tty(const char *path, unsigned int speed);
> > > int control_rtt(char *jlink, char *rtt);
> > > diff --git a/monitor/display.c b/monitor/display.c
> > > index b11b71d5d..598db8080 100644
> > > --- a/monitor/display.c
> > > +++ b/monitor/display.c
> > > @@ -28,6 +28,7 @@
> > > #include "display.h"
> > >
> > > static pid_t pager_pid = 0;
> > > +static int output_width = 0;
> >
> > why not set this to FALLBACK_TERMINAL_WIDTH?
> >
> > > bool use_color(void)
> > > {
> > > @@ -48,7 +49,8 @@ int num_columns(void)
> > >
> > >               if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) < 0 ||
> > >                                                               ws.ws_col == 0)
> > > -                     cached_num_columns = FALLBACK_TERMINAL_WIDTH;
> > > +                     cached_num_columns = output_width > 0 ?
> > > +                             output_width : FALLBACK_TERMINAL_WIDTH;
> > >               else
> > >                       cached_num_columns = ws.ws_col;
> > >       }
> > > @@ -81,12 +83,14 @@ static void wait_for_terminate(pid_t pid)
> > >       }
> > > }
> > >
> > > -void open_pager(void)
> > > +void open_pager(int column)
> > > {
> > >       const char *pager;
> > >       pid_t parent_pid;
> > >       int fd[2];
> > >
> > > +     output_width = column;
> > > +
> > >       if (pager_pid > 0)
> > >               return;
> > >
> > > diff --git a/monitor/display.h b/monitor/display.h
> > > index f3a614b81..70734d590 100644
> > > --- a/monitor/display.h
> > > +++ b/monitor/display.h
> > > @@ -75,5 +75,5 @@ static inline uint64_t print_bitfield(int indent, uint64_t val,
> > >
> > > int num_columns(void);
> > >
> > > -void open_pager(void);
> > > +void open_pager(int column);
> > > void close_pager(void);
> > > diff --git a/monitor/main.c b/monitor/main.c
> > > index 0f5eb4a3b..5996eed40 100644
> > > --- a/monitor/main.c
> > > +++ b/monitor/main.c
> > > @@ -67,6 +67,7 @@ static void usage(void)
> > >               "\t                       Read data from RTT\n"
> > >               "\t-R  --rtt [<address>],[<area>],[<name>]\n"
> > >               "\t                       RTT control block parameters\n"
> > > +             "\t-c, --column [width]   Output width if not a terminal\n"
> >
> > I think we should be using uppercase C.
> >
> > >               "\t-h, --help             Show help options\n");
> > > }
> > >
> > > @@ -90,6 +91,7 @@ static const struct option main_options[] = {
> > >       { "no-pager",  no_argument,       NULL, 'P' },
> > >       { "jlink",     required_argument, NULL, 'J' },
> > >       { "rtt",       required_argument, NULL, 'R' },
> > > +     { "column",    required_argument, NULL, 'c' },
> > >       { "todo",      no_argument,       NULL, '#' },
> > >       { "version",   no_argument,       NULL, 'v' },
> > >       { "help",      no_argument,       NULL, 'h' },
> > > @@ -110,6 +112,7 @@ int main(int argc, char *argv[])
> > >       const char *str;
> > >       char *jlink = NULL;
> > >       char *rtt = NULL;
> > > +     int column = 0;
> > >       int exit_status;
> > >
> > >       mainloop_init();
> > > @@ -121,7 +124,7 @@ int main(int argc, char *argv[])
> > >               struct sockaddr_un addr;
> > >
> > >               opt = getopt_long(argc, argv,
> > > -                                     "r:w:a:s:p:i:d:B:V:MNtTSAE:PJ:R:vh",
> > > +                                     "r:w:a:s:p:i:d:B:V:MNtTSAE:PJ:R:vhc:",
> >
> > Please don’t put this at the end. The vh is at the end on purpose.
> >
> > >                                       main_options, NULL);
> > >               if (opt < 0)
> > >                       break;
> > > @@ -205,6 +208,9 @@ int main(int argc, char *argv[])
> > >               case 'R':
> > >                       rtt = optarg;
> > >                       break;
> > > +             case 'c':
> > > +                     column = atoi(optarg);
> > > +                     break;
> > >               case '#':
> > >                       packet_todo();
> > >                       lmp_todo();
> > > @@ -245,7 +251,7 @@ int main(int argc, char *argv[])
> > >               if (ellisys_server)
> > >                       ellisys_enable(ellisys_server, ellisys_port);
> > >
> > > -             control_reader(reader_path, use_pager);
> > > +             control_reader(reader_path, use_pager, column);
> >
> > I prefer that we use a bit more descriptive variable names here. So either num_columns or pager_width or something like that.
> >
> > >               return EXIT_SUCCESS;
> > >       }
> >
> > Regards
> >
> > Marcel
> >
diff mbox series

Patch

diff --git a/monitor/control.c b/monitor/control.c
index d1ba97d37..00001bf1e 100644
--- a/monitor/control.c
+++ b/monitor/control.c
@@ -1474,7 +1474,7 @@  bool control_writer(const char *path)
 	return !!btsnoop_file;
 }
 
-void control_reader(const char *path, bool pager)
+void control_reader(const char *path, bool pager, int column)
 {
 	unsigned char buf[BTSNOOP_MAX_PACKET_SIZE];
 	uint16_t pktlen;
@@ -1500,7 +1500,7 @@  void control_reader(const char *path, bool pager)
 	}
 
 	if (pager)
-		open_pager();
+		open_pager(column);
 
 	switch (format) {
 	case BTSNOOP_FORMAT_HCI:
diff --git a/monitor/control.h b/monitor/control.h
index 29616c4f1..ad16358b1 100644
--- a/monitor/control.h
+++ b/monitor/control.h
@@ -12,7 +12,7 @@ 
 #include <stdint.h>
 
 bool control_writer(const char *path);
-void control_reader(const char *path, bool pager);
+void control_reader(const char *path, bool pager, int column);
 void control_server(const char *path);
 int control_tty(const char *path, unsigned int speed);
 int control_rtt(char *jlink, char *rtt);
diff --git a/monitor/display.c b/monitor/display.c
index b11b71d5d..598db8080 100644
--- a/monitor/display.c
+++ b/monitor/display.c
@@ -28,6 +28,7 @@ 
 #include "display.h"
 
 static pid_t pager_pid = 0;
+static int output_width = 0;
 
 bool use_color(void)
 {
@@ -48,7 +49,8 @@  int num_columns(void)
 
 		if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) < 0 ||
 								ws.ws_col == 0)
-			cached_num_columns = FALLBACK_TERMINAL_WIDTH;
+			cached_num_columns = output_width > 0 ?
+				output_width : FALLBACK_TERMINAL_WIDTH;
 		else
 			cached_num_columns = ws.ws_col;
 	}
@@ -81,12 +83,14 @@  static void wait_for_terminate(pid_t pid)
 	}
 }
 
-void open_pager(void)
+void open_pager(int column)
 {
 	const char *pager;
 	pid_t parent_pid;
 	int fd[2];
 
+	output_width = column;
+
 	if (pager_pid > 0)
 		return;
 
diff --git a/monitor/display.h b/monitor/display.h
index f3a614b81..70734d590 100644
--- a/monitor/display.h
+++ b/monitor/display.h
@@ -75,5 +75,5 @@  static inline uint64_t print_bitfield(int indent, uint64_t val,
 
 int num_columns(void);
 
-void open_pager(void);
+void open_pager(int column);
 void close_pager(void);
diff --git a/monitor/main.c b/monitor/main.c
index 0f5eb4a3b..5996eed40 100644
--- a/monitor/main.c
+++ b/monitor/main.c
@@ -67,6 +67,7 @@  static void usage(void)
 		"\t                       Read data from RTT\n"
 		"\t-R  --rtt [<address>],[<area>],[<name>]\n"
 		"\t                       RTT control block parameters\n"
+		"\t-c, --column [width]   Output width if not a terminal\n"
 		"\t-h, --help             Show help options\n");
 }
 
@@ -90,6 +91,7 @@  static const struct option main_options[] = {
 	{ "no-pager",  no_argument,       NULL, 'P' },
 	{ "jlink",     required_argument, NULL, 'J' },
 	{ "rtt",       required_argument, NULL, 'R' },
+	{ "column",    required_argument, NULL, 'c' },
 	{ "todo",      no_argument,       NULL, '#' },
 	{ "version",   no_argument,       NULL, 'v' },
 	{ "help",      no_argument,       NULL, 'h' },
@@ -110,6 +112,7 @@  int main(int argc, char *argv[])
 	const char *str;
 	char *jlink = NULL;
 	char *rtt = NULL;
+	int column = 0;
 	int exit_status;
 
 	mainloop_init();
@@ -121,7 +124,7 @@  int main(int argc, char *argv[])
 		struct sockaddr_un addr;
 
 		opt = getopt_long(argc, argv,
-					"r:w:a:s:p:i:d:B:V:MNtTSAE:PJ:R:vh",
+					"r:w:a:s:p:i:d:B:V:MNtTSAE:PJ:R:vhc:",
 					main_options, NULL);
 		if (opt < 0)
 			break;
@@ -205,6 +208,9 @@  int main(int argc, char *argv[])
 		case 'R':
 			rtt = optarg;
 			break;
+		case 'c':
+			column = atoi(optarg);
+			break;
 		case '#':
 			packet_todo();
 			lmp_todo();
@@ -245,7 +251,7 @@  int main(int argc, char *argv[])
 		if (ellisys_server)
 			ellisys_enable(ellisys_server, ellisys_port);
 
-		control_reader(reader_path, use_pager);
+		control_reader(reader_path, use_pager, column);
 		return EXIT_SUCCESS;
 	}