Getting user shell via username

How can I write an if statement that checks what shell a user uses
I tried somthing like that but it didn't work

awk -F: '{ if ($3 >= 1000 && $3 <= 60000) { print $1, $7 } }' /etc/passwd | grep -q "$username /bin/sh"

if [ "$?" = "$username /bin/sh" ] ; then
echo "sh"

else

echo "bash"

fi

any help would be appricated

https://redd.it/ydsvc3
@r_bash

string comparison not working inside while loop

while IFS=',' read -r name position jobs || [ -n "$name" ]
do
if [ ${position} = "bartender" ]; then
echo "$name"
fi
done < "$1"

I have tried set -x, I have tried echoing, I have no idea why it doesn't work. Even when $position clearly contains "bartender", it evaluates to false.

The file looks like this:

Example 1, bartender, A, B, C
Example 2, bartender, C, B, A

https://redd.it/ydur0n
@r_bash

Why does new line (\n) is represented with dot (.) in xxd?

e.g.

$ echo -e '..A\n'
..A

$ echo -e '..A\n' | xxd
00000000: 2e2e 410a 0a ..A..

$ echo -e '..A\n' | xxd -c 1
00000000: 2e .
00000001: 2e .
00000002: 41 A
00000003: 0a .
00000004: 0a .

Can't help but keep thinking why does the new line (\\n or 0a) is represented with dot (.) in xxd?

https://redd.it/ydxj4t
@r_bash

killing a process that is spawned from a subsubnoscript

Hi everyone, hope you all doing great.

so a have a noscript1 which spawn a number of noscript2 as background process.

noscript2 spawns noscript3 in noscript3 i run a specific program, i store the process id of noscript3 in a file and retrive it later when needed, at some point i just want to kill the whole program without leaving process behind, how can i do that?

noscript3 is spawned from a function in noscript2 and is run as a background process. noscript3_function &

i tried:

1. kill -KILL -noscript3_pid
2. pkill -P noscript3_pid

but those keep the spawned processes running.

&#x200B;

https://redd.it/ye10s4
@r_bash

What is going on here ?

I need an explanation. Looks like an easter egg, lol !

This is fine:

cat > ~/bin/test.py <<EOF

#no interpreter line

print ("hello world.")

EOF

chmod +x ~/bin/test.py

~/bin/test.py

/home/miguel/bin/test.py: line 2: syntax error near unexpected token \"hello world."

/home/miguel/bin/test.py: line 2: \print ("hello world.")

&#x200B;

But what is going here ? :

cat > ~/bin/test2.py <<EOF

# no interpreter line

import json

print ("hello world.")

EOF

chmod +x ~/bin/test2.py

~/bin/test2.py

Them the program stops, the mouse cursor changes to a doubled cross until I click on the left mouse button.

The question is : From what hell this cursor came from and why my noscript is blocked until I clicked the left mouse button ?

For sure it is related to the import json, but how , why ?

Of course, adding the interpreter line to the noscript, everything works as expected.

&#x200B;

PS: I had trouble with inline code,,,,things get messy. I hope formatting it is fixed now.

https://redd.it/ye7435
@r_bash

Need some help massaging some filenames

Hello all,
I have a large number of music files that needs some TLC.

Here is a sample;
'Polygyny - Absentee Husband (Pt. 1)-mH2vMMl3BDg.mp3'
'Primal Scream - 2013 - Full Length - Official-bdCraT9_wk4.mp3'
'Primal Scream - All Fall Down-4wi2bi9-ZUI.mp3'
'Prince - 1999 (Official Music Video)-rblt2EtFfC4.mp3'
'Pulp - After You (Soulwax Remix)-KTuLLBqs4Xg.mp3'
'Robert Wyatt - Arauco-JPbsBPkIAy0.mp3'
'Robert Wyatt - At Last I Am Free-6xQx4G11pRo.mp3'
'Rufus & Chaka Khan - Ain'\\''t Nobody (Official Video) Remastered Audio HQ-hrWTxRgd4Wk.mp3'
'Saint Etienne - Avenue-h05qHruTmb8.mp3'
"Sandkings - All's Well With The World-rf6-5-9efM8.mp3"
'She Was a Vision-o6YyRX5TIYc.mp3'
'Sisters of Mercy - Alice--GwWra1sQgo.mp3'
'Soul II Soul - Back To Life (However Do You Want Me) (Official Music Video)-TB54dZkzZOY.mp3'

I would like to remove anything inside parenthesis, also at the end of every filename there is that random group of characters between a '-' dash and the '.mp3'.
Now, the parenthesis I could probably finagle a solution to, but the random characters I don't know how to do.

Can some bright young bash wiz help out an old man?

https://redd.it/yeknqt
@r_bash

Special noscript for get full information about any linux system

Hello everybody!I serve a lot of linux system and when I connect to them I want to get simple information about system: hostname, list last commands, information about memory, hardware and other. I wrote a little noscript and I want go get a good critique. Please look at this noscript and give me some advice how I can make this code better, thank you.

My Script: https://pastebin.com/Pv2VZ44B. You can use this noscript, if you like it

A little denoscription about algorithms this noscript:

Get Info about noscript and weather by ip info :) - `curl, l2.io/ip,` [`wttr.in`](https://wttr.in)
Get General Info - uname, lsb_release, whoami, who
Get Hardware Info - `sudo lshw`
Get Network Info - ip add show
Get Memory Info (>!this code i take on the internet - perhaps stackoverflow.com!<) - `ps`
Get Disk Info - df
Get Network Trafic Info - (>!this code i take on the internet - perhaps stackoverflow.com!<) - `proc/net/dev`
Get Logins and History Info - last, lastb, /etc/paswd, history

https://redd.it/yemqeo
@r_bash

Bash readline command not recognized

Hey there,

I am currently customizing my inputrc to set new keybindings for the set -o vi mode.

[readline library\]

There is a command list in man(1) bash.

```

previous-screen-line

Attempt to move point to the same physical screen column on the previous physical screen line. This will not have the desired effect if the current readline line does not take up more than one physical line or if point is not greater than the length of the prompt plus the screen width.

next-screen-line

Attempt to move point to the same physical screen column on the next physical screen line. This will not have the desired effect if the current readline line does not take up more than one physical line or if the length of current readline line is not greater than the length of the prompt plus the screen width.

```

All the other commands work as expected. Yet those two do not.

Any1 has any idea why ?

Thanks for your time :)

https://redd.it/yep02s
@r_bash

getopts switches

Created a noscript which is using getopts,and has 4 switches -> 3,p,d and h. How could I limit the usage to something like:
- if h is used, no other switch should be used
- switch 3 and p should not be used together
I would like to know if there's way of accomplishing this without using tests outside the while loop.

Thanks

https://redd.it/yetohi
@r_bash

Security: Prevent Override of Bash Builtins?

Greetings Bash Hackers,

I have been using Bash daily for several years as both a noscripting/glue language, and as a more general-purpose programming language. Something that has bothered me for a long time is Bash's lack of reserved words. Before you continue reading, you'll want to put your tin foil hat on.

In some other languages, there is a relatively large set of builtin functions that cannot be overridden for security reasons. Bash, on the other hand, has relatively few of these (i.e. time, if, function, et cetera), and some of the things that you'd expect to be reserved (i.e. builtin, declare, readonly, et cetera), are not. Maybe I'm wrong, but to me: this seems like an oversight and a pretty big security hole. I can see the utility of being able to mock out some of these builtins temporarily for unit testing purposes, but not being able to toggle that behavior seems like a huge issue. Someone with malicious intent, for example, could try to inject function definitions in the environment inherited by the noscript, or could use improperly sanitized noscript parameters to define malicious functions of the same name as builtins.

Going through Bash's info page, there is a "restricted mode" that prevents shell builtins from being overridden with functions of the same name, but that also toggles off quite a few other nice bash features that most people would want to keep in place, even if they toggled off the ability to override builtins. Not all, but many of these features disabled by restricted mode, don't appear to have major security issues that would warrant disabling them; or the security issues are easy to mitigate with decent input sanitization or similar security practices.

So, I have a few questions:

Is it unreasonable to expect Bash users to be able to toggle off features in a piecemeal fashion, instead of the all-or-none approach that restricted mode provides? Are all of the features that it toggles off equally dangerous and as difficult to mitigate?
If this is not an unreasonable goal, is there a way to toggle off just the ability to override builtins that I have just not been able to figure out yet?

To better illustrate this issue, here is an example of something I have considered that doesn't quite work. Since 'function' is a reserved word, I have used that to create a function that wraps builtins, like so:

function readonly() { builtin readonly $@; }

This would work great, if someone hasn't already overridden the 'builtin' builtin. You could 'unset' any potentially set/inherited builtin functions prior to invoking them, (including the 'builtin' builtin), but 'unset' could have been overridden as well. You could exclude the use of the 'builtin' builtin inside of the function definition above, but then its just a function that calls itself over-and-over again. You could make sure that any function you set in the way illustrated above is readonly, using the 'readonly' or 'declare' builtin, but you still have the same chicken-and-egg problem. The 'readonly' and 'declare' builtins could easily be overridden with a function the noscript maliciously (or accidentally) inherits from the environment, making it untrusted as well.

Based on the experiment above, I don't see a way to prevent the overriding of builtins using just the reserved words Bash has available. I also have not found a shell option (shopt) or bash flag that can be passed when invoking Bash that lets you prevent builtin overrides, without also toggling off a bunch of other useful features. Is there another version of the bash '-r' (aka restricted mode) flag that only toggles off the ability to override builtins? Is there some other, completely different, way to do this that I have not considered? Am I crazy for even wanting to do this?

https://redd.it/yeucrq
@r_bash

How to escape single quotes?

I know this question has been asked many times already, however none of the answers have worked for me. I am trying to escape single quotes so I can use variables in this shell noscript. The noscript recognizes specific links from a text file, then sends a command that replaces a specific string in a different file with a image link. It works fine, however not when I try to add a variable. It just says "No such file or directory" whenever executed.

#!/bin/bash
bash -c 'examplelink.com() { sed -i -e "/e_embed.set_thumbnail(url/s/\".*\"/\"exampleimagelink.com\"/" '$1'/cogs/Embeds.py; }; cd '$var'/'$2'; . ./file.txt';
var="/to/folder";

I have tried several things.

'"'"'$var'"'"'
"'$var'"
\'$var'\''

As well as other stuff including different combinations of the shown examples.

https://redd.it/yewd51
@r_bash

Shell expansion question

I'm trying to noscript the publishing and promotion of content-views in RH Satellite (The Foreman), and the versions aren't always equal, so I need to have dynamically named variables, like repo1\_ver, repo2\_ver, etc. The versions evaluate to 1.0, or 5.0, or whatever, always in an x.y format.

&#x200B;

Here's a simplified version of what I'm doing

CV_LIST=(test0 test1 test2 test_space)

get_version() {
echo -e "===============\nWhat this does\n==============="
for CV in "${CV_LIST[@]}" ; do
declare -g ${CV}_VER=$(hammer --csv --no-headers content-view version list --content-view $CV | sed -n '1'p | awk -F, '{ print $3 }')
echo "${CV}_VER"
done

echo -e "\n\n===============\nWhat I want this to do\n==============="

echo $test0_VER
echo $test1_VER
echo $test2_VER
echo $test_space_VER

}

get_version

The output is

===============
What this does
===============
test0_VER
test1_VER
test2_VER
test_space_VER


===============
What I want this to do
===============
1.0
1.0
1.0
2.0

I want it to do that because I want to take the output of ${CV}\_VER and use it in the next hammer command to promote the content views to the next version in another loop, like

&#x200B;

for ENV in Dev QA Mgmt PreProd Prod ; do hammer content-view version promote --content-view $CV --to-lifecycle-environment $ENV --version ${CV}_VER ; done

I know I could create another array and do like this

NEWVERS=(${test0_VER} ${test1_VER} ${test2_VER} ${test_space_VER})
for CV in "${CV_LIST[@]}" ; do
for VER in "${NEWVERS[@]}" ; do
for ENV in Dev QA Mgmt PreProd Prod ; do hammer content-view version promote --content-view $CV --to-lifecycle-environment $ENV --version $VER ; done
done
done

In fact, that's what I did. I just want to know if what I would prefer to do is possible, or if I'm trying to do something that can't be done.

https://redd.it/yf9kbp
@r_bash

Help reading a file that consists of single lines of commands, and then running those commands.

My aim is a noscript that reads lines of commands from a file, execute each line and then add the exit code from each to an array. Some lines have multiple commands. Forgive my mobile formatting, or lack thereof. My noscript is something like:

arr=()
while IFS= read -r line
do
#execute line
"${line}"
#add exit code from command to array
arr+=($?)
done < config.txt

And config.txt has commands like:
! -z $variable
crontab -l | grep -q "dothething.txt"
-d "/some/folder/path"
$inferesting_info > file.txt; #do some other things here; And one more thing here
...
My problem is, the commands are not being executed properly, and I'm thinking there's got to be a way to encapsulate each line of command(s) to have it parse correctly and then unwrap it to run iI: with a combination of parenthesis or quotations, or something. I just can't figure it out. Any help is greatly appreciated!

[https://redd.it/yfbnln
@r_bash

Part of my noscript is not working i need some help

am trying to automate image creation, am a total noob still, i know my code is probably an abomination too lol, anyway am trying to move 3 images from the source folder then apply some image processing then add the 3 images into one thumbnail and outputting it, everything worked just fined but the part that has " `# this part is not working i dont know why` " before maeking the code specify directories it was working, i appreciate the help :DD

&#x200B;

am here in the terminal trying to use the 3 directories in the noscript

~/coding/Fullnoscript$ ls
out processing sources 'test (copy).sh' test.sh

&#x200B;

#!/bin/bash

imgsu=sources
target=processing
outfold=out

i=0

ls -Q $imgsu/ | head -3 | xargs -i mv $imgsu/{} $target/


echo "Initiating"


for file in $target/* ; do
if [ -e "$file" ] ; then
mv "$file" $target/fileinput_$i.png
i=$((i+1))
fi
done

echo "Naming Finished!"

for file in $target/* ; do # this part is not working i dont know why
if [ -e "$file" ] ; then
convert $target/$file -resize 910x910 -fuzz 1% -trim +repage $target/$file
fi
done

echo "Resize Finished!"

convert -size 1920x1080 canvas:black \
-gravity southwest $target/fileinput_1.png -geometry +40+10 -composite \
-gravity southeast $target/fileinput_2.png -geometry +40+10 -composite \
-gravity north $target/fileinput_0.png -geometry +0+10 -composite \
$outfold/out.png

https://redd.it/yfmasz
@r_bash

Using python within readarray

I'm having issues trying to use python within readarray.. the error I get is "unexpected EOF while looking for matching ')'. This happens to be the first line of readarray. Any advice?

readarray -t ARR < <(python3 - <<-EOF
import os, itertools
....
....
EOF
)

https://redd.it/yfr3ts
@r_bash

Isolate first colum of output ?

Hi all,

&#x200B;

I'm currently writin a noscript to enable vpn connections on certain conditions on Ubuntu 20.04 machines exclusively, and to do so i need to get the exact name of the VPN connection.

&#x200B;

I use this command to grep all the vpn connection of the machine :

nmcli con | grep vpn

And the output looks like that :

VPN-Name xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx vpn --

&#x200B;

&#x200B;

What i would like is to get only the name in a text file.

I tried to use the awk command like so :

nmcli con | grep vpn | awk '{ print $1, $NF }'

But if the VPN name is two words then it gets only the first word :

For a VPN called "VPN Company Name" it will output "VPN" only.

&#x200B;

What i want is get the full name of the VPN but i couldn't find any option that could isolate names with the nmcli connection command.

https://redd.it/yfkb40
@r_bash

I created a noscript combining a few ssh commands

Hi everyone,

I combined my frequently used ssh, scp and sshfs commands into a simple noscript.
Github

Feel free to criticize

https://redd.it/yg0diu
@r_bash

Is it possible to iterate through array elements without using FOR or WHILE?

I wonder WHY:

printf 'Each element: %s\n' "${foo[@]}" will print each element of the array foo[@] but I still need to loop through the same array with for i in "${foo[@]}"? Is this because of printf()'s built-in logic? E.g.: sudo apt install "${foo[@]}" would be nice but it doesn't work for me.

Thanks!

https://redd.it/yg1t1k
@r_bash

dd from image to SD card: "short write on character device"

Hi,

I'm using MACOS but I think the OS is not the problem here.I tried to backup my 64GB SD card using DD, with:

sudo dd if=/dev/rdisk2 of=Miyoo64Gb.dmg status=progress bs=16M

That goes well. I put in another SD card (same size) and try to restore that same image with:sudo dd if=Miyoo64Gb.dmg of=/dev/rdisk2 status=progress bs=1m

However, it fails and I then get the error"short write on character device"

When I try to restore the image to SD card using the desktop (Disk Utility.app) it fails.

Another thing I tried is to mount both the .dmg image as wel as the new SD card and just copy the content from the image to the SD card, but then I get the error destination is full!

I've tried several SD cards, the image is fine, I can mount it and browse succesfully/any thoughts what can be the issue?

Another thing I was thinking of is the blocksize in the command (1M in my case), but then, I used the same blocksize for writing as reading, so I guess that cannot be the problem.

PLEASE HELP, I tried everything and I'm desperate howto get my SD card cloned.

https://redd.it/yg0sqt
@r_bash

Using output of one curl request in the next noscript

Hey guys, sorry if this has been asked here before, but I couldn’t find anything specific to my scenario and I don’t use bash that much.

I use a curl post request to get an address from an api, that I’m currently copy pasting as the location for the noscript I use next. The issue is the first noscript outputs other stuff too like status codes, upload speeds etc and I just need the url and without the quotation marks and then use it for the second noscript, what’s the simplest way to go about this in a bash file?

https://redd.it/yg7qcl
@r_bash

How to determine what block device is mapped to /dev/mapper/

I have an external drive mapped to /dev/mapper/backup.

My question is how do I verify what block device said mapping is mapped to?

My backup drive appears as /dev/sda, what would the command/noscript look like in order to verify that /dev/mapper/backup is in fact /dev/sda?

My god the amount of research I've done trying to figure how to do this is insane. Please send help, thank you

https://redd.it/yg91x4
@r_bash