Check for any one of the background commands run by a loop exits with success

I have a loop that runs bluetooth command in the background (tries to connect to bluetooth devices with a timeout of X seconds).

If any one of those commands run by the loop exits (which can only mean either timeout of X seconds has passed after attempting to connect devices or a device has connected, which is usually immediately), then exit the noscript, else do something.

connect_trusted() {
local device
for device in $(bluetoothctl devices Trusted | cut -f 2 -d ' '); do
# this command runs in background, exiting immediately with success on
# connection or failure after timeout of 5 seconds has passed
bluetoothctl -t 5 connect "$device" &
done
}

# if even just 1 device was connected, exit noscript immediately since no more action is needed
if connect_trusted; then
exit 0
# else, launch bluetooth menu after 5 seconds have passed (implied when bluetooth command exits with failure)
else
do_something
fi

------------

How to check that "any one of the `bluetoothctl -t 5 connect "$device" &` commands" exited with success to then exit the noscript, else `do_something`?

https://redd.it/1ifdcpg
@r_bash

Anyone ever try to use Tmux + friends to build a TUI app?

Anyone ever try to use Tmux as the basis for a TUI for a bash app? Perhaps combined with `dialog`/`whiptail`, `fzf`, `bat`, `watch`, etc. It could even include some tmux plugins.

TUI apps similar to `lazygit`, `lazydocker` and wtfutil could possibly be quickly written as a bash noscript inside of a tmux layout.


Possible skeleton (untested):

#!/bin/bash

# app_name - denoscription of app_name
# usage:
#   app_name <options>

set -euo pipefail

_dispatch() {
  case "$1" in
    "_start_tui")
      shift
      _start "$@"
      ;;
    "_pane0_1")
      shift
      _loop _pane0_1
      ;;
    "_pane0_2") 
      shift
      _loop _pane0_2
      ;;
    *)
      _start_tmux "$@"
      ;;
  esac
}

_loop() {
  while sleep 5; do "$@" || true; done
}

_start_tmux() {
  # enable tmux to run inside of tmux
  unset TMUX TMUX_PANE TMUX_PLUGIN_MANAGER_PATH tmux_version
  export TMUX_SOCKET="$(mktemp -u)"
  # re-run self with $1=_layout
  exec tmux \
    -S "$TMUX_SOCKET" \
    -p ~/.config/app_name \
    -f ~/.config/app_name/tmux.conf \
    -c "'$0' _start_tui $(printf '%q ' "$@")"
}

_start_tui() {
  # TODO: unbind the prefix key, to disable the default keybinds.
  # TODO: capture ctrl-c/INT to kill tmux (not individual pane noscripts)

  _layout "$@" &
  _loop _pane0_0
}

_layout() {
  # TODO: layout panes.  examples:
  tmux split-window -h -t 0.0 "$0" _pane0_1
  tmux split-window -v -t 0.1 "$0" _pane0_2
  # TODO: settings
  # TODO: app key bindings
  # TODO: process command line options
}

# definitions of panes

_pane0_0() {
  # noscript for window 0 pane 0

  date
}

_pane0_1() {
  # noscript for window 0 pane 1

  top
}

_pane0_2() {
  # TODO: noscript for window 0 pane 2
}

_dispatch "$@"

https://redd.it/1ies4ig
@r_bash

Can't seem to get the correct pid when using this bash noscript I'm working on. Any help?

When using this noscript: https://pastecode.io/s/py42w4xn (via usernoscripts on unraid)

The pid in the logs is not the same as the one that's showing when i run a ps aux | grep "[s]leep 10"

It always seems to be off one. What am I doing wrong here?

The goal is to basically reset a timer every time there's a update from inotifywait and then at the end perform a command.

Thanks!

https://redd.it/1ielvng
@r_bash

Total Newbie at Bash Scripting

I'm trying to create a noscript to download and datestamp YouTube videos. I can download the videos, but it comes down with the name given by it's creator. I want to append the upload date to the front of the filename. Any help is appreciated. My noscript so far:

read -p "Enter YouTube URL: " yt_url

echo "YouTube URL = ${yt_url}"



read -p "Enter upload date: " upload_date

echo "Upload Date = ${upload_date}"



file=$(yt-dlp --get-filename -o "%(noscript)s.mp4" $yt_url)

echo "File = ${file}"



yt-dlp -f mp4 "$yt_url"



https://redd.it/1iedal0
@r_bash

Custom bash noscript dependency graph

Hi all!
Some time ago I started to write a little bash noscript to check some kubernetes stuffs I need to check. By the time this noscript has become so huge with a lot of functions and variables. Sometimes I need to edit some things but I’m starting to get lost in the functions. Is there any automated way to create a graph that contains all the functions and them dependencies?

Thank you!

https://redd.it/1ig9d5f
@r_bash

How would you efficiently process every line in a file? while read is 70x slower than Python

I have written a lot of shell noscripts over the years and in most cases for parsing and analyzing text I just pipe things around to grep, sed, cut, tr, awk and friends. The processing speeds are really fast in those cases.

I ended up writing a pretty substantial shell noscript and now after seeding its data source with around 1,000 items I'm noticing things are slow enough that I'm thinking about rewriting it in Python but I figured I'd post this to see if anyone has any ideas on how to improve it. Using Bash 4+ features is fine.

I've isolated the slowness down to Bash looping over each line of output.

The amount of processing I'm doing on this text isn't a ton but it doesn't lend itself well to just piping data between a few tools. It requires custom programming.

That means my program ends up with code like this:

while read -r matched_line; do
# This is where all of my processing occurs.
echo "${line}"
done <<< "${matches}"

And in this case `${matches}` are lines returned by grep. You can also loop over the output of a program too such as `done < <(grep ...)`. On a few hundred lines of input this takes 2 full seconds to process on my machine. Even if you do nothing except echo the line, it takes that amount of time. My custom logic to do the processing isn't a lot (milliseconds).

I also tried reading it into an array with `readarray -t matched_lines` and then doing a `for matched_line in "${matched_lines[@]}"`. The speed is about the same as while read.

Alternatively if I take the same matches content and use Python using code like this:

with open(filename) as file:
for line in file:
print(line)

This finishes in 30ms. It's around 70x faster than Bash to process each line with only 1,000 lines.

Any thoughts? I don't mind Python but I already wrote the tool in Bash.



https://redd.it/1ifvg1m
@r_bash

Url-encode get string with multiple arguments?

I have one string that's like
action=query&format=json&list=allpages&aplimit=max&apfilterredir=nonredirects&apprefix=Wp/akz&apcontinue=Wp/akz/Bréhéville
If I put it into the url without encoding, it breaks because it contains special characters. If I put the whole thing into --data-urlencode it encodes the &s and treats it all as one argument.
Soo, what do I do?

https://redd.it/1iftomw
@r_bash

can you explain what this does?

echo '[q]sa[ln0=aln256%Pln256/snlbx]sb5567320342535949633984860024054390510049758475925810612727383477870370412074937779308150930912981042snlbxq'|dc



(It is in a single line)

https://redd.it/1ighyqf
@r_bash

I need your help

Hello, I am quite new on Linux and I wanted to make a bash noscript that has my Linux desktop environment, customisation, apps etc at once because I switch computers quite often and don't want the hassle of doing these every time I switch devices. If it's possible a yt video would be very helpful but I appreciate all the answers. Thank you!

https://redd.it/1ifj9me
@r_bash

nesting command substitutions

My goal is to use dmenu to browse a small set of applications. A list of such applications is in \~/prj/dmenus/favorites/a.txt. If I invoke $(cat ~/prj/dmenus/favorites/a.txt | dmenu)

I get just what I'm after. If I invoke

$(cat ~/prj/dmenus/favorites/a.txt | dmenu -fn 'Droid Sans Mono-18')

I get a output that is nicer to read. Next step, I would like to put the formatting options in a file. I can access that file and read it into a variable by another command substitution.

Example:x=$(<~/.config/dmenu/layout.txt); echo $x yields -fn 'Droid Sans Mono-18'

That is as far as I get. Can't seem to execute in the out command substitution.

$(cat ~/prj/dmenus/favorites/a.txt | dmenu $x)

usage: dmenu [-bfiv] [-l lines] [-p prompt] [-fn font] [-m monitor]

[-nb color] [-nf color] [-sb color] [-sf color] [-w windowid]

Not what I want Similarly, if I use

$(cat ~/prj/dmenus/favorites/a.txt | dmenu $(<~/.config/dmenu/layout.txt))

usage: dmenu [-bfiv] [-l lines] [-p prompt] [-fn font] [-m monitor]

[-nb color] [-nf color] [-sb color] [-sf color] [-w windowid]

Same failure. I bet the solution is really simple, and will enlighten me immensely.

I am using ubuntu 24.04 with fluxbox.

Thanks

Ti











https://redd.it/1ih44b2
@r_bash

Is there a way to get History without <enter>?

Hi, I'd like to get a past command of history for example !1900 but without enter, so I can rewrite that command for this instance and then manually I will do then <enter> for this new changed command?

Regards!

https://redd.it/1ih5bpo
@r_bash

Sed/awk help

Hi, I have text files that contain lists of numbers. Each number is on a separate line. Some of the numbers have forward slashes in the middle (eg 11152/3), some of them don't (eg 11276), which is fine.

However due to the way I collected the data, there are some lines that just have an assortment of slashes and spaces on them and nothing else.

Is there any way I can use sed or awk to get rid of the unwanted slashes whilst keeping the wanted ones?

https://redd.it/1ihd4yv
@r_bash

looking for a way to have a yes or no option at the end of a noscript to start another noscript or exit.

I have a simple backup noscript that creates archives of data. At the end of the noscript it encrypts and then uploads to a cloud server.

I'd like to make this into two noscripts with an option at the end of the first to run the second noscript or exit. i.e, I don't always want to encrypt and upload.

Any ideas?

https://redd.it/1ihisxo
@r_bash

Window Tiling Script w/ xdotool and wmctrl not persistent after switch workspaces

So I'm running xfce4 as my DE (w/ xfwm4 as the WM) and the window tiling that comes default is awesome \*if\* you're using a monitor(s) with normal dimensions. I got a nice ultrawide monitor a while back and the tiling, while still effective, doesn't quite tile the way it would on a standard monitor. I've been meaning to write a noscript to tile more effectively on an ultrawide monitor for a while now and I **finally got around to it** about a week ago.

Things are going great and it works exactly as expected (sort of). I pasted the code below (but I must warn you I'm still pretty new to bash noscripting so there might be an simpler way to accomplish the same thing). I basically find what window is active with xdotool, figure out what monitor that window is on (with some wizardry I found on StackExchange), and tile the window with wmctrl based on the argument passed to the noscript. Then I just programmed each of the variations with different arguments to different keyboard shortcuts and \*chef's kiss\*

**Here's the problem:** every time I change workspaces and change back, one or more of the windows I've tiled with my noscript move around to a different position and size. Is there any reason this could be happening with my noscript or could it be something else in the window manager overriding things?



`# This noscript is meant to tile windows into smaller regions`

`# than what is available by default in xfce4.`

`#`

`# Ultra-wide monitors are effective as a seamless dual monitor,`

`# but window tiling acts different. This is a fix for that issue.`

`# Don't bother using this noscript on a standard monitor. It will`

`# work, but the windows will be unusable.`

`#`

`# This noscript will separate the monitor into 8 regions, 4 on`

`# the top half of the screen and 4 on the bottom, with each`

`# given a letter signifier representing a physical mapping of`

`# a keyboard, like so:`

`#`

`# -----------------`

`# | Q | W | E | R |`

`# |---------------|`

`# | A | S | D | F |`

`# -----------------`

`#`

`# Additionally, there will be 4 more regions with 100% height,`

`# from left to right:`

`#`

`# -----------------`

`# | | | | |`

`# | H | J | K | L |`

`# | | | | |`

`# -----------------`

`#`

`# This gives a total of 12 tiling variations available that`

`# mimic default tiling on a standard monitor. Simply pass`

`# the letter designation of the region you wish to tile your`

`# focused window to as the only argument.`

`#`

`# For example:`

`# 'window-tile.sh -Q' tiles the active window to the top-left`

`# region.`

`#`

`# Each variation can be tied to keyboard shortcuts for easy tiling.`

`# I used <ctrl>+<super>+<letter>`







`# Get active window as decimal using xdotool`

`FOCUSED=$(xdotool getactivewindow)`



`# Convert decimal value to hex for use with wmctrl`

`FOCUSED=$( echo "obase=16; $FOCUSED" | bc )`

`FOCUSED=$( echo "0x0$FOCUSED" | awk '{print tolower($0)}' )`



`# Thanks to terdon from the PowerUser StackExchange for this`

`# next section to determine the current monitor.`



`## Get screen info`

`screen1=($(xrandr | grep -w connected | awk -F'[ +]' '{print $1,$3,$4}' |`

`head -n 1))`

`screen2=($(xrandr | grep -w connected | awk -F'[ +]' '{print $1,$3,$4}' |`

`tail -n 1))`



`## Figure out which screen is to the right of which`

`if [ ${screen1[2]} -eq 0 ]`

`then`

`right=(${screen2[@]});`

`left=(${screen1[@]});`

`else`

`right=(${screen1[@]});`

`left=(${screen2[@]});`



`fi`



`## Get window position`

`pos=$(xwininfo -id $(xdotool getactivewindow) | grep "Absolute upper-left X" |`

`awk '{print $NF}')`



`## Which screen is this window displayed in? If $pos`

`## is greater than the offset of the rightmost screen,`

`## then the window is on the right hand one`



`# Parse resolution of current monitor and assign to`

`# $WIDTH and $HEIGHT`

`if [ "$pos" -gt "${right[2]}" ]`

`then`

`# echo

"${right[0]} : ${right[1]}"`

`IFS=x read -r WIDTH HEIGHT <<< ${right[1]}`

`else`

`# echo "${left[0]} : ${left[1]}"`

`IFS=x read -r WIDTH HEIGHT <<< ${left[1]}`

`fi`



`# Tile the focused window based on argument passed.`

`# Position and size is determined by the resolution of the current moniter:`

`# if $HEIGHT=1440 and I want the window to equal half the height of the`

`# screen, I would use $(( $HEIGHT / 2 )). Enter 'man wmctrl' in your`

`# terminal prompt to get more information on the wmctrl command.`



`if [ $1 = '-Q' ]`

`then`

`wmctrl -ir $FOCUSED -e 0,0,0,$(( $WIDTH / 4 )),$(((( $HEIGHT / 2 )) - 1))`

`elif [ $1 = '-W' ]`

`then`

`wmctrl -ir $FOCUSED -e 0,$(( $WIDTH / 4 )),0,$(( $WIDTH / 4 )),$(((( $HEIGHT / 2 )) - 1))`

`elif [ $1 = '-E' ]`

`then`

`wmctrl -ir $FOCUSED -e 0,$(( 2 * (( $WIDTH / 4 )))),0,$(( $WIDTH / 4 )),$(((( $HEIGHT / 2 )) - 1))`

`elif [ $1 = '-R' ]`

`then`

`wmctrl -ir $FOCUSED -e 0,$(( 3 * (( $WIDTH / 4 )))),0,$(( $WIDTH / 4 )),$(((( $HEIGHT / 2 )) - 1 ))`

`elif [ $1 = '-A' ]`

`then`

`wmctrl -ir $FOCUSED -e 0,0,$(( $HEIGHT / 2)),$(( $WIDTH / 4 )),$(( $HEIGHT / 2 ))`

`elif [ $1 = '-S' ]`

`then`

`wmctrl -ir $FOCUSED -e 0,$(( $WIDTH / 4 )),$(( $HEIGHT / 2 )),$(( $WIDTH / 4 )),$(( $HEIGHT / 2 ))`

`elif [ $1 = '-D' ]`

`then`

`wmctrl -ir $FOCUSED -e 0,$(( 2 * (( $WIDTH / 4 )))),$(( $HEIGHT / 2 )),$(( $WIDTH / 4 )),$(( $HEIGHT / 2 ))`

`elif [ $1 = '-F' ]`

`then`

`wmctrl -ir $FOCUSED -e 0,$(( 3 * (( $WIDTH / 4 )))),$(( $HEIGHT / 2 )),$(( $WIDTH / 4 )),$(( $HEIGHT / 2 ))`

`elif [ $1 = '-H' ]`

`then`

`wmctrl -ir $FOCUSED -e 0,0,0,$(( $WIDTH / 4 )),$(( $HEIGHT ))`

`elif [ $1 = '-J' ]`

`then`

`wmctrl -ir $FOCUSED -e 0,$(( $WIDTH / 4 )),0,$(( $WIDTH / 4 )),$(( $HEIGHT ))`

`elif [ $1 = '-K' ]`

`then`

`wmctrl -ir $FOCUSED -e 0,$(( 2 * (( $WIDTH / 4 )))),0,$(( $WIDTH / 4 )),$(( $HEIGHT ))`

`elif [ $1 = '-L' ]`

`then`

`wmctrl -ir $FOCUSED -e 0,$(( 3 * (( $WIDTH / 4 )))),0,$(( $WIDTH / 4 )),$(( $HEIGHT ))`

`else`

`echo "Argument required"`

`fi`



https://redd.it/1iirxja
@r_bash

help in named pipes

Hi everyone,

I have a question, I was studying a Linux privilege escalation course, and I came across a systemctl abuse https://gtfobins.github.io/gtfobins/systemctl/#sudo

and then I ask myself why not to do it but get interactive shell, using two named pipes, example:

f1=/tmp/infifo
f2=/tmp/outfifo
mkfifo $f1 $f2
sf=mktemp.service
echo -e "Service\nExecStart=eval \"/bin/bash < $f1 > $f2 &\"\nInstall\nWantedBy=multi-user.target" > $sf
sudo systemctl link $sf
sudo systemctl enable $sf --now
cat $f2 &
cat > $f1

but it did not work, but if I tried it without systemctl, am I using pipes incorrect?
and can you help me understanding named pipes and how to use it?

https://redd.it/1ij1agl
@r_bash

Authorized one way but unauthorized the other

When I run curl commands independently in iTerm2, I am able to get a file back that I need with no issue. However, when I run those same commands in a bash noscript, I get unauthorized. The tokens are the same both ways. I can give more info if needed, but why would this be happening?

https://redd.it/1ij5qpj
@r_bash

is anything like "rm all except this, this2, this3"

Hi, I should remove some files.jpg (from 20 +/-) except 3 of them

rm all except DSC1011.jpg Dsc1015.jpg Dsc1020.jpg

what will be the command?

and of course for your GIANT HELPING ALWAYS GENIUSES

https://redd.it/1ijda50
@r_bash

Archstrap - Bootsrap Arch Linux from an existing Linux distro
https://github.com/wick3dr0se/archstrap

https://redd.it/1ikanhw
@r_bash

Depth first or breadth first after learning Linux terminal & Shell noscripting?


Few things on my mind but unsure if I am eligible to learn it..

- gitlab (Mastering gitlab 12)

- Elasticsearch(Not sure of the text to read)

- DNS & BIND (Pro DNS & BIND 10)

- DBA (Pro MySQL)


(Obviously looking into devops route)

https://redd.it/1ikkw26
@r_bash

line buffering vs block buffering

Hi, after trying appending to a file with awk some weird occurrence happened

awk -i inplace '{print $0} ENDFILE{print "endoffile"}' somefile

the next command in terminal finish immediately and throws an error with exit status 1:

cat -A
cat: -: input file is output file

Now the `grep` (which has `--line-buffered` as a possible flag) does fine

grep -

So, my suspicion was `awk -i inplace` has done something wrong, and the [inplace extension manual](https://www.gnu.org/software/gawk/manual/htmlnode/Extension-Sample-Inplace.html) does suggest so

>redirect gawk's standard output to /dev/null

Slightly different from suggested, but this works

awk -i inplace '{print $0} ENDFILE{print "endoffile"}' somefile &>/dev/null

also `sed --in-place` has no problem at all

sed -i '$r /dev/stdin' somefile <<< "endoffile"

So what is the cause of this, and is the manual slightly wrong? It doesn't seems awk -i inplace is like sed -i emulation, like suggested. Also, is &>/dev/null mandatory to follow inplace extension?



https://redd.it/1ikudxt
@r_bash