The product laws


How to select rectangles in TMUX

Just add to your .tmux.conf file:

set-window-option -g mode-keys vi
bind-key -T copy-mode-vi 'v' send -X begin-selection
bind-key -T copy-mode-vi 'y' send -X copy-selection-and-cancel
bind-key -T copy-mode-vi 'r' send -X rectangle-toggle



Screen brightness control on i3wm for Lenovo X240 (Ubuntu)

First ensure that you have the right permissions to write to the device by adding a new rule for udev (create a new file like /etc/udev/rules.d/99-backlight) with these lines:

ACTION=="add", SUBSYSTEM=="backlight", RUN+="/bin/chgrp video /sys/class/backlight/%k/brightness"
ACTION=="add", SUBSYSTEM=="backlight", RUN+="/bin/chmod g+w /sys/class/backlight/%k/brightness"
ACTION=="add", SUBSYSTEM=="leds", RUN+="/bin/chgrp video /sys/class/leds/%k/brightness"
ACTION=="add", SUBSYSTEM=="leds", RUN+="/bin/chmod g+w /sys/class/leds/%k/brightness"

You’ll have reboot your system for the changes to take effect.

Now you need to add you user to the video group.

You’ve to install the tool light :

sudo apt install light

And finally you have to add this to your i3wm config

bindsym XF86MonBrightnessUp exec light -A 10
bindsym XF86MonBrightnessDown exec light -U 10

How to set the brightness of your monitor in Ubuntu 20.04

xrandr --output <output> --brightness 0.5

Use xrandr --listmonitors to get the name of your monitor




apue.h header from Advanced Programming in the Unix Environment

 * Our own header, to be included before all standard system headers.
#ifndef	_APUE_H
#define	_APUE_H

#define _POSIX_C_SOURCE 200809L

#if defined(SOLARIS)		/* Solaris 10 */
#define _XOPEN_SOURCE 600
#define _XOPEN_SOURCE 700

#include 		/* some systems still require this */
#include 	/* for winsize */
#if defined(MACOS) || !defined(TIOCGWINSZ)

#include 		/* for convenience */
#include 		/* for convenience */
#include 		/* for offsetof */
#include 		/* for convenience */
#include 		/* for convenience */
#include 		/* for SIG_ERR */

#define	MAXLINE	4096			/* max line length */

 * Default file access permissions for new files.

 * Default permissions for new directories.

typedef	void	Sigfunc(int);	/* for signal handlers */

#define	min(a,b)	((a) < (b) ? (a) : (b))
#define	max(a,b)	((a) > (b) ? (a) : (b))

 * Prototypes for our own functions.
char	*path_alloc(size_t *);				/* {Prog pathalloc} */
long	 open_max(void);					/* {Prog openmax} */

int		 set_cloexec(int);					/* {Prog setfd} */
void	 clr_fl(int, int);
void	 set_fl(int, int);					/* {Prog setfl} */

void	 pr_exit(int);						/* {Prog prexit} */

void	 pr_mask(const char *);				/* {Prog prmask} */
Sigfunc	*signal_intr(int, Sigfunc *);		/* {Prog signal_intr_function} */

void	 daemonize(const char *);			/* {Prog daemoninit} */

void	 sleep_us(unsigned int);			/* {Ex sleepus} */
ssize_t	 readn(int, void *, size_t);		/* {Prog readn_writen} */
ssize_t	 writen(int, const void *, size_t);	/* {Prog readn_writen} */

int		 fd_pipe(int *);					/* {Prog sock_fdpipe} */
int		 recv_fd(int, ssize_t (*func)(int,
		         const void *, size_t));	/* {Prog recvfd_sockets} */
int		 send_fd(int, int);					/* {Prog sendfd_sockets} */
int		 send_err(int, int,
		          const char *);			/* {Prog senderr} */
int		 serv_listen(const char *);			/* {Prog servlisten_sockets} */
int		 serv_accept(int, uid_t *);			/* {Prog servaccept_sockets} */
int		 cli_conn(const char *);			/* {Prog cliconn_sockets} */
int		 buf_args(char *, int (*func)(int,
		          char **));				/* {Prog bufargs} */

int		 tty_cbreak(int);					/* {Prog raw} */
int		 tty_raw(int);						/* {Prog raw} */
int		 tty_reset(int);					/* {Prog raw} */
void	 tty_atexit(void);					/* {Prog raw} */
struct termios	*tty_termios(void);			/* {Prog raw} */

int		 ptym_open(char *, int);			/* {Prog ptyopen} */
int		 ptys_open(char *);					/* {Prog ptyopen} */
pid_t	 pty_fork(int *, char *, int, const struct termios *,
		          const struct winsize *);	/* {Prog ptyfork} */

int		lock_reg(int, int, int, off_t, int, off_t); /* {Prog lockreg} */

#define	read_lock(fd, offset, whence, len) \
			lock_reg((fd), F_SETLK, F_RDLCK, (offset), (whence), (len))
#define	readw_lock(fd, offset, whence, len) \
			lock_reg((fd), F_SETLKW, F_RDLCK, (offset), (whence), (len))
#define	write_lock(fd, offset, whence, len) \
			lock_reg((fd), F_SETLK, F_WRLCK, (offset), (whence), (len))
#define	writew_lock(fd, offset, whence, len) \
			lock_reg((fd), F_SETLKW, F_WRLCK, (offset), (whence), (len))
#define	un_lock(fd, offset, whence, len) \
			lock_reg((fd), F_SETLK, F_UNLCK, (offset), (whence), (len))

pid_t	lock_test(int, int, off_t, int, off_t);		/* {Prog locktest} */

#define	is_read_lockable(fd, offset, whence, len) \
			(lock_test((fd), F_RDLCK, (offset), (whence), (len)) == 0)
#define	is_write_lockable(fd, offset, whence, len) \
			(lock_test((fd), F_WRLCK, (offset), (whence), (len)) == 0)

void	err_msg(const char *, ...);			/* {App misc_source} */
void	err_dump(const char *, ...) __attribute__((noreturn));
void	err_quit(const char *, ...) __attribute__((noreturn));
void	err_cont(int, const char *, ...);
void	err_exit(int, const char *, ...) __attribute__((noreturn));
void	err_ret(const char *, ...);
void	err_sys(const char *, ...) __attribute__((noreturn));

void	log_msg(const char *, ...);			/* {App misc_source} */
void	log_open(const char *, int, int);
void	log_quit(const char *, ...) __attribute__((noreturn));
void	log_ret(const char *, ...);
void	log_sys(const char *, ...) __attribute__((noreturn));
void	log_exit(int, const char *, ...) __attribute__((noreturn));

void	TELL_WAIT(void);		/* parent/child from {Sec race_conditions} */
void	TELL_PARENT(pid_t);
void	TELL_CHILD(pid_t);
void	WAIT_PARENT(void);
void	WAIT_CHILD(void);

#endif	/* _APUE_H */

GCC-9 and Ubuntu kernel error

if you Linux suddenly stop compiling the kernel or kernel modules from packages (nvidia, virtualbox) check that you are not using gcc-9 as default C compiler, it has a problem with some parameters needed to compile with protections for the last Intel bugs, showing in the broken compilation like this:

error: '-mindirect-branch' and '-fcf-protection' are not compatible

switching to gcc-8 should fix the problem:

sudo update-alternatives --install /usr/bin/gcc gcc  /usr/bin/gcc-8 1

Delay when using ESC in tmux?

Just set:

set -s escape-time 0

In your tmux.conf configuration file.


How to install vowpalwabbit in Ubuntu 19.04 (Disco Dingo)

Well nothing really changed from my last post on the subject (for Ubuntu 17.10):

$ sudo apt-get install libboost-program-options-dev 
$ sudo apt-get install libboost-python-dev
$ sudo apt-get install libvw-dev
$ sudo apt-get install libvw0
$ sudo apt-get install vowpal-wabbit
$ sudo apt-get install vowpal-wabbit-dbg
$ pip install vowpalwabbit

Works like a charm.


Monday, assorted links

  1. What to Expect From Search in 2019 With Google’s John Mueller & Ashley Berman Hale

Monday, assorted links

  1. Seven Myths in Machine Learning Research