Given the following table
$ connmanctl services
*AO MyNetwork wifi_dc85de828967_68756773616d_managed_psk
OtherNET wifi_dc85de828967_38303944616e69656c73_managed_psk
AnotherOne wifi_dc85de828967_3257495245363836_managed_wep
FourthNetwork wifi_dc85de828967_4d7572706879_managed_wep
AnOpenNetwork wifi_dc85de828967_4d6568657272696e_managed_none
I'd like to be able to connect to a network, e.g. OtherNET, using the string OtherNET rather than the long wifi_dc85de828967_38303944616e69656c73_managed_psk, as I don't want to count the times I press Tab and/or check that the wifi_ line in the prompt corresponds to the intended network.
Is this possible with connman only? Or do I really have to write a wrapper myself?
The man page of connmanctl contains
services
Shows a list of all available services. This includes the
nearby wifi networks, the wired ethernet connections, blue‐
tooth devices, etc. An asterisk in front of the service
indicates that the service has been connected before.
and
connect service
Connects to the given service. Some services need a so-
called provisioning file in order to connect to them, see
connman-service.config(5).
which both don't say much about the format of the output or the use of the command.
Similarly, the wiki on Arch Linux refers to the last column as the second field beginning with wifi_.
Since nobody has answered yet, I have found some spare time to code the following wrapper, which basically does the following
keeps reading as long as the input is not exit;
when an input is provided which starts with connect, the following word is used to pattern-match one line (only the first matching line) from connman services; the last field of this line (the one which starts with wifi_) is forwarded to connmanctl connect;
any other non-empty input is forwarded to connmanctl as it is.
a certain number (to be passed through the variable NOINPUTS_BEFORE_EXIT whose default is 3) of empty inputs causes the script to exit.
The script is the following
#!/usr/bin/env bash
name=$(basename $0)
noinputs_before_exit=${NOINPUTS_BEFORE_EXIT:=3}
while [[ $cmd != 'exit' ]]; do
echo -n "$name " 1>&2
read cmd
if [[ -z "$cmd" ]]; then
(( --noinputs_before_exit == 0 )) && exit
else
noinputs_before_exit=$NOINPUTS_BEFORE_EXIT
if [[ $cmd =~ ^connect\ ]]; then
connmanctl connect $(connmanctl services | awk '/'"${cmd#* }"'/ { print $NF; exit }')
else
connmanctl $cmd
fi
fi
done
The script limitations are at least the following:
(less importantly, to me) I have no idea whether it meets any security requirements;
it does not allow Tab-completion;
(most importantly, to me) it does not use the readline library, so line editing impossible.
I've seen all the examples for setting a connectTimeout, however, I am looping through a list of servers and if the current server takes more than 10sec, then move on to the next one if not, then assign this server to a variable.
Based on knowledge learned in previous question, my script is as follows
SERVERS="abc123 abc124 abc125"
for n in $SERVERS ; do
if [ ssh -o connectTimeout=10 "$n" ] ; then
SERVER="$n"
if
done
Obviously this doesn't work. The if throws [too many arguments] and I actually want to say if [ ssh "$n" <= connectTime=10 ] ; then SERVER="$n"...etc. however, I'm not a bash expert, so I don't know if that is an acceptable argument or not, so it's why I'm reaching out to the experts. Thanks for all feedback.
if [ ssh -o connectTimeout=10 "$n" ]
Remove the "[" and "]" characters here. "[" and "]" aren't part of the if statement syntax. They invoke a command named [ (also known as the test command) which performs certain kinds of tests. You commonly see if and [ used together, but they'e two separate commands.
Something like this should work:
for n in $SERVERS
do
if ssh -o connectTimeout=10 "$n"
then
SERVER="$n"
fi
done
I know that this topic has been discussed many times, but none of the answers helped me. For the record, i'm running Debian.
The deal is: I bought an usb powered led lamp, which is very simple and doesn't even have an on/off switch (it works and is always on). I want to be able to turn it on/off via command line. Here's what i tried:
echo on > /sys/bus/usb/devices/usb1/power/level # turn on
echo suspend > /sys/bus/usb/devices/usb1/power/level # turn off
which is what i've found on many forums. Turning "on" works, but "suspending" yields
-su: echo: write error: Invalid argument
for every usbN. I also tried
echo "0" > "/sys/bus/usb/devices/usbX/power/autosuspend_delay_ms"
which doesn't give an error, but also doesn't do anything (again, for every usbN)
trying
echo "usb1" > /sys/bus/usb/drivers/usb/unbind
works only for more "inteligent" devices, like the keyboard, the mouse, or the usb wifi card. What i mean is that only tyhose devices are turned off, other usbN don't give an error, but the lamp never goes off.
the contents of /sys/bus/usb/devices/ are
1-0:1.0 1-1:1.0 1-2:1.0 1-2:1.2 2-0:1.0 4-0:1.0 4-1:1.0 6-0:1.0 8-0:1.0 8-2:1.0 usb2 usb4 usb6 usb8
1-1 1-2 1-2:1.1 1-2:1.3 3-0:1.0 4-1 5-0:1.0 7-0:1.0 8-2 usb1 usb3 usb5 usb7
i tried to do
echo device_name > /sys/bus/usb/drivers/usb/unbind
with every single one of them, but only the devices usbN and N-M react, the ones of the form n-m:x.y yield
tee: /sys/bus/usb/drivers/usb/bind: No such device
(i tried putting in, for instance, "1-0:1.0", "1-0\:1.0" and "1-0\:1.0", all gave the same result).
One last thing, what is shown after executing
lsusb -t
does not change when i plug or unplug the lamp.
Any ideas?
Turn off device ID 2-1:
echo '2-1' |sudo tee /sys/bus/usb/drivers/usb/unbind
Turn device ID 2-1 back on:
echo '2-1' |sudo tee /sys/bus/usb/drivers/usb/bind
In my case, using device ID 2-1 controls power to my usb stick, and as a consequence controls the light.
TIP: If they work for you in Debian, create an alias for them to make life easier for you later.
Hope this helps,
Su
If all you want to do is reset a USB device to fix it once it gets into a broken state, then using the bind/unbind usbfs special files can be a bit of a pain (since device IDs can change, and they're a bit tricky to identify precisely if you don't want to rebind other devices). In this case I've found it much easier to use the vendor and product IDs given by lsusb with usb_modeswitch. For example, if I identify my wireless adapter using:
$ lsusb
Bus 001 Device 042: ID 7392:7811 Edimax Technology Co., Ltd EW-7811Un 802.11n Wireless Adapter [Realtek RTL8188CUS]
Bus 001 Device 035: ID 0409:005a NEC Corp. HighSpeed Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
I can then reset the wireless adapter using:
$ sudo usb_modeswitch -v 0x7392 -p 0x7811 --reset-usb
If you have more than one device attached with the same vendor and product IDs then usb_modeswitch provides bus and device number flags. For the wireless adapter example above I'd add -b 1 -g 42 to the flags.
Try this code it works for me (Only for rooted)
String[] cmdline = { "su", "-c", "echo '1-1' >/sys/bus/usb/drivers/usb/unbind" };
try {
Runtime.getRuntime().exec(cmdline);
} catch (IOException e) {
Log.e("MainActivity","Failed"+e);
}
and for bind again do this
String[] cmdline = { "su", "-c", "echo '1-1' >/sys/bus/usb/drivers/usb/bind" };
try {
Runtime.getRuntime().exec(cmdline);
} catch (IOException e) {
Log.e("MainActivity","Failed"+e);
}
Does anyone know of a way to query OS X in order to find out how much time is actually left before it enters either system sleep or activates the display sleep (or even disk sleep), either via the command line, or any other method (Ruby or Objective-C for instance)?
I thought something like pmset via the command line might have offered this information, but it appears to only show and update what the current settings are, rather than allow feedback of where in the cycle the OS currently is.
My requirement is that I currently have a Ruby script that I'd like to run only when I'm not using the machine and a simple 'whatcher script' would allow this, but what to 'watch' is the thing I need a little help with.
It seems like there should be a simple answer, but so far I've not found anything obvious. Any ideas?
Heres a bash script to show the commands, which are a little complicated. The idea is that the user sets the system sleep time in the energy saver preference pane. The system will actually go to sleep when no device attached to the computer has moved for that time. So to get the time until the system goes to sleep we need the difference between those 2 results.
#!/bin/bash
# this will check how long before the system sleeps
# it gets the system sleep setting
# it gets the devices idle time
# it returns the difference between the two
#
# Note: if systemSleepTimeMinutes is 0 then the system is set to not go to sleep at all
#
systemSleepTimeMinutes=`pmset -g | grep "^[ ]*sleep" | awk '{ print $2 }'`
if [ $systemSleepTimeMinutes -gt "0" ]; then
systemSleepTime=`echo "$systemSleepTimeMinutes * 60" | bc`
devicesIdleTime=`ioreg -c IOHIDSystem | awk '/HIDIdleTime/ {print $NF/1000000000; exit}'`
secondsBeforeSleep=`echo "$systemSleepTime - $devicesIdleTime" | bc`
echo "Time before sleep (sec): $secondsBeforeSleep"
exit 0
else
echo "The system is set to not sleep."
exit 0
fi
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I've just introduced a friend to GNU Screen and they're having a hard time getting used to it. That makes me think about the essential things he needs to know about the excellent Screen utility, the same things that you'd think worthwhile to teach someone, a beginner, from the ground up. What are some analogies and handy tips for remembering binds, etc.?
It would be awesome.
I've been using Screen for over 10 years and probably use less than half the features. So it's definitely not necessary to learn all its features right away (and I wouldn't recommend trying). My day-to-day commands are:
^A ^W - window list, where am I
^A ^C - create new window
^A space - next window
^A p - previous window
^A ^A - switch to previous screen (toggle)
^A [0-9] - go to window [0-9]
^A esc - copy mode, which I use for scrollback
I think that's it. I sometimes use the split screen features, but certainly not daily. The other tip is if screen seems to have locked up because you hit some random key combination by accident, do both ^Q and ^A ^Q to try to unlock it.
I couldn't get used to screen until I found a way to set a 'status bar' at the bottom of the screen that shows what 'tab' or 'virtual screen' you're on and which other ones there are. Here is my setup:
[roel#roel ~]$ cat .screenrc
# Here comes the pain...
caption always "%{=b dw}:%{-b dw}:%{=b dk}[ %{-b dw}%{-b dg}$USER%{-b dw}#%{-b dg}%H %{=b dk}] [ %= %?%{-b dg}%-Lw%?%{+b dk}(%{+b dw}%n:%t%{+b dk})%?(%u)%?%{-b dw}%?%{-b dg}%+Lw%? %{=b dk}]%{-b dw}:%{+b dw}:"
backtick 2 5 5 $HOME/scripts/meminfo
hardstatus alwayslastline "%{+b dw}:%{-b dw}:%{+b dk}[%{-b dg} %0C:%s%a %{=b dk}]-[ %{-b dw}Load%{+b dk}:%{-b dg}%l %{+b dk}] [%{-b dg}%2`%{+b dk}] %=[ %{-b dg}%1`%{=b dk} ]%{-b dw}:%{+b dw}:%<"
sorendition "-b dw"
[roel#roel ~]$ cat ~/scripts/meminfo
#!/bin/sh
RAM=`cat /proc/meminfo | grep "MemFree" | awk -F" " '{print $2}'`
SWAP=`cat /proc/meminfo | grep "SwapFree" | awk -F" " '{print $2}'`
echo -n "${RAM}kb/ram ${SWAP}kb/swap"
[roel#roel ~]$
Ctrl+A ? - show the help screen!
If your friend is in the habit of pressing ^A to get to the beginning of the line in Bash, he/she is in for some surprises, since ^A is the screen command key binding. Usually I end up with a frozen screen, possibly because of some random key I pressed after ^A :-)
In those cases I try
^A s and ^A q block/unblock terminal scrolling
to fix that. To go to the beginning of a line inside screen, the key sequence is ^A a.
You can remap the escape key from Ctrl + A to be another key of your choice, so if you do use it for something else, e.g. to go to the beginning of the line in bash, you just need to add a line to your ~/.screenrc file. To make it ^b or ^B, use:
escape ^bB
From the command line, use names sessions to keep multiple sessions under control. I use one session per task, each with multiple tabs:
screen -ls # Lists your current screen sessions
screen -S <name> # Creates a new screen session called name
screen -r <name> # Connects to the named screen sessions
When using screen you only need a few commands:
^A c Create a new shell
^A [0-9] Switch shell
^A k Kill the current shell
^A d Disconnect from screen
^A ? Show the help
An excellent quick reference can be found here. It is worth bookmarking.
Some tips for those sorta familiar with screen, but who tend to not remember things they read in the man page:
To change the name of a screen window is very easy: ctrl+A shift+A.
Did you miss the last message from screen? ctrl+a ctrl+m will show it again for you.
If you want to run something (like tailing a file) and have screen tell you when there's a change, use ctrl+A shift+m on the target window. Warning: it will let you know if anything changes.
Want to select window 15 directly? Try these in your .screenrc file:
bind ! select 11
bind # select 12
bind \# select 13
bind $ select 14
bind % select 15
bind \^ select 16
bind & select 17
bind * select 18
bind ( select 19
bind ) select 10
That assigns ctrl+a shift+0 through 9 for windows 10 through 19.
Ctrl+A is the base command
Ctrl+A N = go to the ***N***ext screen
Ctrl+A P = go to the ***P***revious screen
Ctrl+A C = ***C***reate new screen
Ctrl+A D = ***D***etach your screen
http://www.debian-administration.org/articles/34
I wrote that a couple of years ago, but it is still a good introduction that gets a lot of positive feedback.
I "must" add this: add
bind s
to your .screenrc, if You - like me - used to use split windows, as C-a S splits the actual window, but C-a s freezes it. So I just disabled the freeze shortcut.
Ctrl+a is a special key.
Ctrl+a d - [d]etach, leave programs (irssi?) in background, go home.
Ctrl+a c [c]reate a new window
Ctrl+a 0-9 switch between windows by number
screen -r - get back to detached session
That covers 90% of use cases. Do not try to show all the functionality at the single time.
Not really essential not solely related to screen, but enabling 256 colors in my terminal, GNU Screen and Vim improved my screen experience big time (especially since I code in Vim about 8h a day - there are some great eye-friendly colorschemes).
The first modification I make to .screenrc is to change the escape command. Not unlike many of you, I do not like the default Ctrl-A sequence because of its interference with that fundamental functionality in almost every other context. In my .screenrc file, I add:
escape `e
That's backtick-e.
This enables me to use the backtick as the escape key (e.g. to create a new screen, I press backtick-c, detach is backtick-d, backtick-? is help, backtick-backtick is previous screen, etc.). The only way it interferes (and I had to break myself of the habit) is using backtick on the command line to capture execution output, or pasting anything that contains a backtick. For the former, I've modified my habit by using the BASH $(command) convention. For the latter, I usually just pop open another xterm or detach from screen then paste the content containing the backtick. Finally, if I wish to insert a literal backtick, I simply press backtick-e.
There is some interesting work being done on getting a good GNU screen setup happening by default in the next version of Ubuntu Server, which includes using the bottom of the screen to show all the windows as well as other useful machine details (like number of updates available and whether the machine needs a reboot). You can probably grab their .screenrc and customise it to your needs.
The most useful commands I have in my .screenrc are the following:
shelltitle "$ |bash" # Make screen assign window titles automatically
hardstatus alwayslastline "%w" # Show all window titles at bottom line of term
This way I always know what windows are open, and what is running in them at the moment, too.
I use the following for ssh:
#!/bin/sh
# scr - Runs a command in a fresh screen
#
# Get the current directory and the name of command
wd=`pwd`
cmd=$1
shift
# We can tell if we are running inside screen by looking
# for the STY environment variable. If it is not set we
# only need to run the command, but if it is set then
# we need to use screen.
if [ -z "$STY" ]; then
$cmd $*
else
# Screen needs to change directory so that
# relative file names are resolved correctly.
screen -X chdir $wd
# Ask screen to run the command
if [ $cmd == "ssh" ]; then
screen -X screen -t ""${1##*#}"" $cmd $*
else
screen -X screen -t "$cmd $*" $cmd $*
fi
fi
Then I set the following bash aliases:
vim() {
scr vim $*
}
man() {
scr man $*
}
info() {
scr info $*
}
watch() {
scr watch $*
}
ssh() {
scr ssh $*
}
It opens a new screen for the above aliases and iff using ssh, it renames the screen title with the ssh hostname.
I like to set up a screen session with descriptive names for the windows. ^a A will let you give a name to the current window and ^a " will give you a list of your windows.
When done, detach the screen with ^a d and re-attach with screen -R
I like to use screen -d -RR to automatically create/attach to a given screen. I created bash functions to make it easier...
function mkscreen
{
local add=n
if [ "$1" == '-a' ]; then
add=y
shift;
fi
local name=$1;
shift;
local command="$*";
if [ -z "$name" -o -z "$command" ]; then
echo 'Usage: mkscreen [ -a ] name command
-a Add to .bashrc.' 1>&2;
return 1;
fi
if [ $add == y ]; then
echo "mkscreen $name $command" >> $HOME/.bashrc;
fi
alias $name="/usr/bin/screen -d -RR -S $name $command";
return 0;
}
function rmscreen
{
local delete=n
if [ "$1" == '-d' ]; then
delete=y
shift;
fi
local name=$1;
if [ -z "$name" ]; then
echo 'Usage: rmscreen [ -d ] name
-d Delete from .bashrc.' 1>&2;
return 1;
fi
if [ $delete == y ]; then
sed -i -r "/^mkscreen $name .*/d" $HOME/.bashrc;
fi
unalias $name;
return 0;
}
They create an alias to /usr/bin/screen -d -RR -S $name $command. For example, I like to use irssi in a screen session, so in my .bashrc (beneath those functions), I have:
mkscreen irc /usr/bin/irssi
Then I can just type irc in a terminal to get into irssi. If the screen 'irc' doesn't exist yet then it is created and /usr/bin/irssi is run from it (which connects automatically, of course). If it's already running then I just reattach to it, forcibly detaching any other instance that is already attached to it. It's quite nice.
Another example is creating temporary screen aliases for perldocs as I come across them:
mkscreen perlipc perldoc perlipc
perlipc # Start reading the perldoc, ^A d to detach.
...
# Later, when I'm done reading it, or at least finished
# with the alias, I remove it.
rmscreen perlipc
The -a option (must be first argument) appends the screen alias to .bashrc (so it's persistent) and -d removes it (these can potentially be destructive, so use at own risk). xD
Append:
Another bash-ism that I find convenient when working a lot with screen:
alias sls='/usr/bin/screen -ls'
That way you can list your screens with a lot fewer keystrokes. I don't know if sls collides with any existing utilities, but it didn't at the time on my system so I went for it.
^A A switches back to the screen you just came from.
Ctrl + A is a great special character for Unix people, but if you're using screen to talk to OpenVMS, then not being able to ^A is going to make you bald prematurely.
In VMS, if you're editing a DCL command prior to execution from the history buffer, Insert mode is off (it has to be for a few reasons I won't get into here) ... to turn it on so you don't over-type your command rather than space things out, you have to hit `^A.