GNU coreutils: signal specifications . commands “kill” and “nohup”

$kill -l
 1) SIGHUP	 2) SIGINT	 3) SIGQUIT	 4) SIGILL	 5) SIGTRAP
 6) SIGABRT	 7) SIGBUS	 8) SIGFPE	 9) SIGKILL	10) SIGUSR1
11) SIGSEGV	12) SIGUSR2	13) SIGPIPE	14) SIGALRM	15) SIGTERM
16) SIGSTKFLT	17) SIGCHLD	18) SIGCONT	19) SIGSTOP	20) SIGTSTP
21) SIGTTIN	22) SIGTTOU	23) SIGURG	24) SIGXCPU	25) SIGXFSZ
26) SIGVTALRM	27) SIGPROF	28) SIGWINCH	29) SIGIO	30) SIGPWR
31) SIGSYS	34) SIGRTMIN	35) SIGRTMIN+1	36) SIGRTMIN+2	37) SIGRTMIN+3
38) SIGRTMIN+4	39) SIGRTMIN+5	40) SIGRTMIN+6	41) SIGRTMIN+7	42) SIGRTMIN+8
43) SIGRTMIN+9	44) SIGRTMIN+10	45) SIGRTMIN+11	46) SIGRTMIN+12	47) SIGRTMIN+13
48) SIGRTMIN+14	49) SIGRTMIN+15	50) SIGRTMAX-14	51) SIGRTMAX-13	52) SIGRTMAX-12
53) SIGRTMAX-11	54) SIGRTMAX-10	55) SIGRTMAX-9	56) SIGRTMAX-8	57) SIGRTMAX-7
58) SIGRTMAX-6	59) SIGRTMAX-5	60) SIGRTMAX-4	61) SIGRTMAX-3	62) SIGRTMAX-2
63) SIGRTMAX-1	64) SIGRTMAX	
$kill -19 `pidof chromium-browse`
$kill -18 `pidof chromium-browse`
$kill -5 `pidof chromium-browse`
$kill -1 `pidof chromium-browse`
$nohup chromium-browser 
nohup: ignoring input and appending output to 'nohup.out'

$
$nohup chromium-browser 
nohup: ignoring input and appending output to 'nohup.out'

$
$kill -1 `pidof chromium-browse`
kill: usage: kill [-s sigspec | -n signum | -sigspec] pid | jobspec ... or kill -l [sigspec]
$kill -3 `pidof chromium-browse`
kill: usage: kill [-s sigspec | -n signum | -sigspec] pid | jobspec ... or kill -l [sigspec]
$nohup chromium-browser 
nohup: ignoring input and appending output to 'nohup.out'



$
$
$
$echo $?
0
$

GNU coreutils: block size related to df command

$df
Filesystem     1K-blocks    Used Available Use% Mounted on
udev             1921644       0   1921644   0% /dev
tmpfs             388676    6508    382168   2% /run
/dev/sda2      475184136 6024592 444951776   2% /
tmpfs            1943372    1460   1941912   1% /dev/shm
tmpfs               5120       4      5116   1% /run/lock
tmpfs            1943372       0   1943372   0% /sys/fs/cgroup
/dev/sda1         523248    3660    519588   1% /boot/efi
tmpfs             388672     104    388568   1% /run/user/1000
$df -h
Filesystem      Size  Used Avail Use% Mounted on
udev            1.9G     0  1.9G   0% /dev
tmpfs           380M  6.4M  374M   2% /run
/dev/sda2       454G  5.8G  425G   2% /
tmpfs           1.9G  1.5M  1.9G   1% /dev/shm
tmpfs           5.0M  4.0K  5.0M   1% /run/lock
tmpfs           1.9G     0  1.9G   0% /sys/fs/cgroup
/dev/sda1       511M  3.6M  508M   1% /boot/efi
tmpfs           380M  104K  380M   1% /run/user/1000
$export DF_BLOCK_SIZE=2k
$df
Filesystem     2K-blocks    Used Available Use% Mounted on
udev              960822       0    960822   0% /dev
tmpfs             194338    3254    191084   2% /run
/dev/sda2      237592068 3012288 222475896   2% /
tmpfs             971686     136    971550   1% /dev/shm
tmpfs               2560       2      2558   1% /run/lock
tmpfs             971686       0    971686   0% /sys/fs/cgroup
/dev/sda1         261624    1830    259794   1% /boot/efi
tmpfs             194336      50    194286   1% /run/user/1000
$export POSIXLY_CORRECT=1
$df
Filesystem     2K-blocks    Used Available Use% Mounted on
udev              960822       0    960822   0% /dev
tmpfs             194338    3252    191086   2% /run
/dev/sda2      237592068 3018782 222469402   2% /
tmpfs             971686     618    971068   1% /dev/shm
tmpfs               2560       2      2558   1% /run/lock
tmpfs             971686       0    971686   0% /sys/fs/cgroup
/dev/sda1         261624    1830    259794   1% /boot/efi
tmpfs             194336      46    194290   1% /run/user/1000
$set -o posix
$df
Filesystem     2K-blocks    Used Available Use% Mounted on
udev              960822       0    960822   0% /dev
tmpfs             194338    3252    191086   2% /run
/dev/sda2      237592068 3018774 222469410   2% /
tmpfs             971686     618    971068   1% /dev/shm
tmpfs               2560       2      2558   1% /run/lock
tmpfs             971686       0    971686   0% /sys/fs/cgroup
/dev/sda1         261624    1830    259794   1% /boot/efi
tmpfs             194336      46    194290   1% /run/user/1000
$
GNU coreutils : backup option related to cp command

$cd  test-folder/
$>1
$>2
$>3
$ls
1  2  3
$cd ..
$>1
$>2
$cp -b 1 test-folder/
$cd test-folder/
$ls
1  1~  2  3
$cd ..
$export SIMPLE_BACKUP_SUFFIX=bc
$cp -b 2 test-folder/
$cd test-folder/
$ls
1  1~  2  2bc  3
$cd ..
$export SIMPLE_BACKUP_SUFFIX=.bc
$cp -b 2 test-folder/
$cd test-folder/
$ls
1  1~  2  2bc  2.bc  3
$


GNU bash exit codes with special meanings

$printenv > /dev/null 
$echo $?
0
$printenv /dev/null 
$echo $?
1
$/dev/null
bash: /dev/null: Permission denied
$echo $?
126
$nocommand
bash: nocommand: command not found...

$
$echo $?
127
$

http://www.tldp.org/LDP/abs/html/exitcodes.html
GNU coreutils with (delimit the option list) feature

$echo "hello" >  --test
$cat --test
cat: unrecognized option '--test'
Try 'cat --help' for more information.
$cat -- --test
hello
$

string and integer variable operation using Javascript

<!DOCTYPE html> 
 
<html lang="en"> 
<head> 
    <title>Chapter 2, Example 1</title> 
</head> 
<body> 
    <script> 
        var myFirstVariable; 
 
        myFirstVariable = "Hello"; 
        alert(myFirstVariable); 
 
        myFirstVariable = 54321; 
        alert(myFirstVariable); 
    </script> 
</body> 
</html>

Key source : Beginning JavaScript, 5th Edition (wrox)

Adding text to html element using JavaScript


<!DOCTYPE html>

<html lang="en">
<head>
<meta charset="utf-8" />
<title>Chapter 1, Example 3</title>
</head>
<body>
<code id="results"></code>
<script>
document.getElementById("results").innerHTML = "Hello World!";
</script>
</body>
</html>

Key source : Beginning JavaScript, 5th Edition (wrox)