Questions tagged [shell]
The shell is Unix's command-line interface. You can type commands in a shell interactively, or write scripts to automate tasks. Use this tag for questions applying to /bin/sh and most compatible shells (ash, bash, ksh, zsh, …). For shell scripts with errors, please check them in http://shellcheck.net before posting here.
11,772
questions
0
votes
1
answer
24
views
How does a trap affect external programs?
When a subshell is entered, traps that are not being ignored shall be set to the default actions
Source: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_28
Apparently,...
- 2,260
0
votes
2
answers
90
views
What is the necessary configuration for enabling tty access for shell on Linux Kernel initramfs?
While echoing, e.g. echo "serial tx to ttyAMA0" > /dev/ttyAMA0 shows output towards serial console terminal on Linux initramfs loaded to /dev/ram0 on an arm64 platform, there's no ...
- 11
0
votes
2
answers
29
views
get latest file on github via script
I am trying to do the same for https://github.com/eneshecan/whatsapp-for-linux/releases as is described here: Download and install latest deb package from github via terminal
but cant get it to work, ...
- 45
-1
votes
1
answer
29
views
How can I format the output of a shell command into columns, but limit the number of columns created?
Say I run
systemctl | grep running | column -t
I get an output that looks like this:
init.scope loaded active running System and Service Manager
session-...
- 119
0
votes
1
answer
24
views
Any CLI pager that display full-screen optionaly (when prompted to)?
I've been using less forever now, and there's one thing I wish it was doing differently.
When I do git log --pretty=oneline --abbrev-commit it switches to full-screen immediately (as the output is ...
- 111
0
votes
1
answer
21
views
Exit out of Insert mode in Bash with Vi keybindings on command run
I have bash set up with Vi keybindings, however when a command finishes running it returns to insert mode rather than movement mode.
I can use bind '"\C-M":vi-movement-mode' in my .bashrc to ...
0
votes
2
answers
37
views
Nested command inside xargs
I have a folder of folders of folders of files. I'm trying to copy all the files to their parent.
The following command doesn't work because dirname "{}" executes before the find command. ...
0
votes
1
answer
21
views
Bash: dirname not working with xargs
The following command:
echo ./test/test2/test23 | xargs -I "{}" echo `dirname "{}"`
Outputs: . (not as expected)
The following command:
echo ./test/test2/test23 | xargs -I "...
2
votes
1
answer
124
views
Stop and Start Shell Script
I have created a simple script to start a process, but I am not sure how to add a stop step since the process is ran/stopped manually
Currently, to start the process, we use a single command line
...
- 45
1
vote
1
answer
35
views
Finding the occurence of a word in a subfolder
Hello i'm trying to find all occurrences of a word in a subfolder. While that seems to be easy i want that for each occurrence we will display the path and the name of the file followed by ' -> ...
- 15
0
votes
1
answer
18
views
"xargs -I" not working for child command
xargs -I not working for child command
Example:
# Not working
ls .... | xargs -n 1 -I % sh -c "cmd $(cmd2 % )"
# working
ls .... | xargs -n 1 -I % sh -c "cmd % "
Is there any ...
- 1
0
votes
1
answer
28
views
How to send expression with variables over ssh?
I can run the followind loop locally
for i in A B C; do mycommand $i; done
Now I am trying to send it over ssh
The following version
ssh myhost for i in A B C; do mycommand $i; done
The following ...
- 2,977
0
votes
0
answers
16
views
How to escape command line to be able to send it by `ssh` to remote host in all cases?
I am composing command line for ssh with the following (Python) code:
def instrument(self, cmd: str) -> str:
return "ssh -A %s" % (cmd)
and this of course failing in some cases, for ...
- 2,977
0
votes
0
answers
23
views
Adding file-user in shell-script
I'm trying to add users with code like this:
asadmin start-domain
asadmin create-file-user --groups=user --target=server-config -authrealmname=file --passwordfile=password.txt a
asadmin create-file-...
0
votes
1
answer
43
views
Shell: Why is there a "duplicate process " on using a pipe and tee?
I'm not very familiar with bash process, and was surprised to see a "duplicate" process running while using pipe and tee. Can you help me understand this?
In the following, the path to the ...
- 1
0
votes
1
answer
63
views
How does "done < file" work in a while loop?
While trying to learn how to manipulate the content of files in bash, I encountered the following code example:
while IFS=, read -r col1 col2
do
echo "I got:$col1|$col2"
done < myfile....
- 121
0
votes
0
answers
63
views
Luci openWRT UCI firewall rule update without position number
Hey all I have been trying find some code that would allow me to update my firewall rule via the UCI.
The way I am currently adding the new rule is like this:
uci add firewall rule
uci set firewall.@...
- 121
0
votes
0
answers
22
views
shell script does not recognize alias even source bashrc where alias are defined [duplicate]
in ~/.bashrc /etc/bashrc, I write
alias multiscp='/root/deploy/multiscp.sh'
and in command line, I could use multiscp like a command multiscp xxx
However, in a shell script, multiscp is not ...
- 135
5
votes
1
answer
874
views
What does command eval "$(/opt/homebrew/bin/brew shellenv)" actually do?
Homebrew requires us to add eval $(/opt/homebrew/bin/brew shellenv) to ~/.zprofile. What does this actually evaluate to and what does this accomplish?
I am a bit new to shell scripting. I know $var is ...
- 53
0
votes
1
answer
62
views
how do I handle a specific output from systemctl?
I am a beginner with bash/shell scripting and I am trying to handle a specific output that comes from systemctl when a specific service is not found. For example, when I run systemctl status xyz the ...
- 3
0
votes
1
answer
32
views
Confused about java -version [duplicate]
For every program/utility on Unix, I would type the name of the program followed by --version to check its version, like so
program --version
If I understand correctly, the double dash -- is used to ...
- 111
0
votes
0
answers
19
views
Can't enable IPv4 forwarding via adb shell
I've got a rooted Android phone and am trying to enable IPv4 forwarding via adb shell. If I do
host$ adb shell
phone$ su -c "echo 1 > /proc/sys/net/ipv4/ip_forward"
then it works just ...
0
votes
2
answers
51
views
Extract value from broken JSON output in Shell
Once I list the backup files from a server, It throws me the output as follows:
{
"backupFiles": [
"XYZ_Backup_2.0.0.0-417_2022_08_14_12_10.gz",
"...
0
votes
0
answers
33
views
How to write regular expression for apt-get so that it excludes package conflicts?
I am trying to install all packages that contain font in their name. I tried apt-get install *font* but packages fontforge and fontforge-nox conflict each other. How should I revise my regex so that ...
- 1
0
votes
1
answer
63
views
keep 2 newest files on folder and delete others
I have a backup folder on my server with autogenerated files. They are consuming 100% of my disk. So i need to create a cron that delete all files but keep the 2 newest.
I have found a code that might ...
- 11
0
votes
6
answers
128
views
search pattern and print in same line
I have a big .txt file in below format
Pin name="AR_OP" status="f"
Pref x=997.6800 y=2327.0400 side=N width=0.0400 depth=0.3750 /
Layer id=1
--
Pin name="...
- 129
0
votes
3
answers
54
views
Combine .csv-files with different amount of lines
Here I asked already for a similar problem.
Now I have 3 .csv-files but one of them has only 1 line.
file1.csv
dog
cats
mouse
file2.csv
001a
002a
003c
file3.csv
WORD
The output should be
dog,001a,...
- 157
1
vote
1
answer
37
views
Combine .csv-files with text between each line
I have two (or maybe more) files:
file1.csv
dog
cats
mouse
file2.csv
001a
002a
003c
If I use paste file1.csv file2.csv the output is
dog 001a
cats 002a
mouse 003c
Of course I can use paste -d ,...
- 157
0
votes
2
answers
40
views
Copy only the folders (and all their content) at the level of source path with rsync
I have the following tree, where f are files while src and d are directories (f could be hidden or not):
src/f1
src/f2
...
src/d1
src/d2
src/d3
...
I want to replicate the same structure in a dst ...
- 27
9
votes
1
answer
829
views
What does a hyphen do next to the argument position in bash shell script? Like ${1-}
I've come across this piece of code from here:
#!/bin/bash
# ...
if [[ "${1-}" =~ ^-*h(elp)?$ ]]; then
echo "Usage..."
exit
fi
I understand what this does is print the ...
0
votes
0
answers
56
views
Zsh: make single file selection smart, stylish, and functionally correct (highlights, completions below cursor, etc)
I would like to have a near-flawless "single file selector" with zsh. So far I haven't seen one in questions as they tend to focus on zle settings for one's command line. Let's say we are ...
- 546
1
vote
0
answers
17
views
Disk usage command not producing expected number of outputs
I want to run disk usage command (du) on both a parent directory (to find the total of all its contents), and then additionally on one of its subdirectories only.
If I try to pass multiple paths into ...
- 174
0
votes
0
answers
70
views
Trying to change "non command" color in kitty terminal (ver. 0.21.2) using the fish (ver. 3.3.1) shell with the oh-my-fish theme slacker
I've been trying to change the color of non-command such as the picture below (the uncompleated 'help')
link to the theme im using in omf: https://github.com/maqboolkhan/omf-theme-slacker
my kitty....
- 25
0
votes
0
answers
19
views
Simple ssh/telnet shell for debugging remote embedded device
I have an embedded device running some aarch64 Linux build, with busybox, but without sudo, nc, sshd, telnetd, /dev/tcp, /dev/udp, etc.
I would like to be able to remote in to run bash commands and ...
0
votes
1
answer
51
views
Cron job to run rmmod not executing at reboot
This is on Proxmox VE 7.3 with Debian 11. I ran crontab -e, added @reboot /home/onboot.sh to the file, saved it, ensured cron is running with systemctl enable cron.serviceand verified it's running at ...
0
votes
1
answer
7
views
install --compare is said to, in some cases, not modify the destination at all - but in which cases?
The man page for install describes the --compare option like so:
-C, --compare
compare each pair of source and destination files, and
in some cases, do not modify ...
- 203
-3
votes
3
answers
69
views
shell script - checking multiple lines if value is smaller than
I have input files (.txt oder .csv)
In this files are different values (sometimes no value -> "").
If ONE of this values is less than 0.001 (or empty -> "") the output should ...
- 157
1
vote
0
answers
51
views
A script causes a parent script to stop
I have a third-party script that runs some complicated stuff.
I run everything from an ssh session (the machine is a headless VM running Ubuntu 20.04).
When I run it interactively, it runs normally.
$ ...
- 406
0
votes
0
answers
31
views
shell stdout to two command and program is stuck
I have a sample shell command to calculate array percentile number
$ time zcat input.txt.gz | head -n 999999 | awk 'BEGIN{FS="\t"}{print $13}' | st
--percentile=97.5
75
real 0m3.532s
...
- 23
0
votes
1
answer
28
views
variable contains $, expansion needed
The script fetches the path of a file via some command and then the mount command runs.
pkgname= #defined here
su -c "apkfile= #defined here &&\
stockapp=$(pm path $pkgname | sed -n '/...
- 140
0
votes
0
answers
15
views
Is the concept of file permission only applicable when access is via shell? [duplicate]
So in Linux we have a concept of file permission. There are three classes: user, group, and others, and there are three types of permissions: read, write, and execute.
Now consider this. You are on a ...
- 83
-1
votes
1
answer
63
views
Is the concept of file permission only applicable when access is via shell?
So in Linux we have a concept of file permission. There are three classes: user, group, and others, and there are three types of permissions: read, write, and execute.
Now consider this. You are on a ...
- 83
0
votes
0
answers
53
views
While loop in root shell
I want to get data from a file which can be read by root only and do some operations on the data.
the code is
su -c "grep $variable $file | while read -r line; do echo $line | xargs -r umount -l; ...
- 140
1
vote
1
answer
55
views
use aliases in bash script
I use aliases in my code, it works the first time and shows the current time, but the second time, when I call it shows past time(time showed before instead of current time)
GNU nano 6.2 ...
1
vote
1
answer
76
views
How do I enable colours by default for common utilites in PowerShell on (Gentoo) Linux?
I'm currently running Gentoo Linux and have installed PowerShell (app-shells/pwsh-bin) as I am a contrarian.
That being said, I am unable to obtain colour by default when running certain commands. ...
- 13
0
votes
0
answers
26
views
How to run ssh commands on a host after mounting via sshfs and avoid 2FA? [duplicate]
I have the following situation. I am able to ssh into a server but it requires 2FA each time I ssh into the server. Let's say that I do not have control over the server's configuration to disable/...
- 101
0
votes
2
answers
41
views
Delete files with similar names
I have been away from scripting for years, so I was wondering if someone can help in the below.
I am migrating from Google Photos to Amazon Photos (about 40k photos). Here is an example of what I ...
- 9
1
vote
0
answers
36
views
How to check whether a shell process has job-control enabled?
Is there a way to programmatically check whether a given (shell) process has job-control enabled?
- 1,736
0
votes
0
answers
67
views
Terminal closes itself when running many python processes
I was trying to run multiple machine learning experiments simultaneously to save time. My OS is Fedora 36, and I use emacs. To automate the experiment I used runs.py
import subprocess
subprocess.run(&...
- 103
2
votes
2
answers
80
views
Is there a character in Linux that can be used at start of a filename to bump it to the top in regular sort order but doesn't require escaping etc?
There are lots of questions/answers explaining what characters one shouldn't use in Linux filenames etc.
I am looking for a non-alpha/numeric character that I can put at the front of a filename to ...
- 255