All Questions
Tagged with bash-functions or bash
27,270 questions
0
votes
1
answer
19
views
Cancel just second command of bash logical AND operator [duplicate]
It often happens that I have some long task running, like compiling a program, running tests or copying large archives. Once I am done with whatever else I was doing, I want to leave the computer ...
5
votes
2
answers
826
views
POSIX sh alternative to using [[ ... ]] in Bash
I am using this code to parse the first argument passed to my script. It error handles and it works just the way I want it:
if [ -z "$action" ]; then
printf "[${c_RED}ERROR${c_RESET}...
0
votes
1
answer
46
views
disable bash job control warning "job specification requires leading `%'"?
I just rebooted one of my systems for the first time in several months, restarted tmux and my usual set of bash shells for tailing various log files, and noticed that running fg n (i.e. fg followed by ...
- 84.9k
2
votes
3
answers
181
views
bash syntax: what does '[@]+' mean? [duplicate]
I have a script that parses command line arguments.
The intro to the loop to iterate over the argument array looks like this:
for arg in ${args[@]+"${args[@]}"}; do
Can someone explain this ...
3
votes
6
answers
391
views
How can I use sed to chain append lines from a text file, add it as a suffix to the text on the same lines numbers on another file, and so on?
I've tried using sed for this. I've tried putting the lines of interest in variables as well.
I have two examples I want to achieve for now. Lets say I have thousands of urls in a file called links....
- 69
0
votes
0
answers
56
views
how to convert hex memory dump to Docsis config file?
Hex memory dump is Docsis config file. Is it possible to convert this hex dump info valid Docsis config file? Preferably, using Perl and DOCSIS::ConfigFile module. (or Python scripts, python-docsis). ...
- 1,473
3
votes
3
answers
899
views
How do I ensure a bash script argument is a specific value?
The following script is supposed to check $1 and see if it is a specific value. It only works when one Bash [[... =~ ...]] regex check is passed in an if statement.
The error is: When more than one ...
4
votes
1
answer
196
views
Choice of field separator affects sort's ordering
Suppose we have a script named test_sort in our $PATH with the following contents:
#!/bin/bash
function echo_text () {
printf -- "%s\n" "$fc$oc$fs$lc"
printf -- "%s\n&...
- 4,476
1
vote
1
answer
44
views
White spacing is causing variable to not contain all text in result
Disclaimer: I am brand new to bash
I'm building a dialog box and trying to get some Docker commands to populate results.
I am using this to return a result, which works for the most part.
result=($(...
- 13
0
votes
2
answers
142
views
Process sed capture group with a bash function before replacement: "sh: 1: <bash function>: not found"
So, I was playing around with this answer, when I found that neither
printf_stdin () {
read input
printf "$input"
}
sed "/lorem ipsum foobar/ {
s/'/'\"'\"'/g
s/\...
- 145
0
votes
1
answer
41
views
`xargs sh -c` not picking up last argument (vs `for i in $(...)`) [duplicate]
I just wanted to build a simple bash script that inverted a 'hex color code' (made up of 3 pairs of 2-digit hexadecimal numbers, in the format #RRGGBB). In my first code block I attempt to perform ...
- 53
2
votes
1
answer
36
views
Shell bracket list wildcard doesn't work with variable [duplicate]
The following works:
ls {000/487,000/488,000/489,000/490,000/491,000/492}
...many files being listed
But this doesn't. Why ?
LIST=000/487,000/488,000/489,000/490,000/491,000/492
ls {$LIST}
ls: cannot ...
- 659
11
votes
1
answer
1k
views
Is there any difference between [[ -n $1 ]] and [[ $1 ]] in bash?
The test [[ -n $1 ]] yields True if the length of string is non-zero.
But I've seen elsewhere and have tried using just [[ $1 ]] without the primary -n and it seems to have the same effect.
Is there ...
- 436
1
vote
0
answers
55
views
Running XFCE on Debian Trixie. Bash history is not saving any sudo commands
Bash history works OK for except for sudo commands.
Code from .bashrc follows.
How can I modify the behaviour to include anything starting with sudo?
NOTE. This behaviour is the same with a brand new ...
- 11
1
vote
1
answer
72
views
Bash: only the first long option is being processed
Suppose we have the file ./testing with contents
#!/bin/bash
# Flags
# Source: https://stackoverflow.com/a/7948533/31298396
TEMP=$(getopt -o ''\
--long first,second \
-...
- 145
2
votes
1
answer
102
views
Bash: function in a script with flags
Using https://stackoverflow.com/a/7948533/31298396, we can implement flags for a script testing as follows:
#!/bin/bash
# Flags
# Source: https://stackoverflow.com/a/7948533/31298396
TEMP=$(getopt ...
- 145
5
votes
2
answers
541
views
Why doesn't the pwd nullary built-in error when provided an argument, whereas the nullary/unary exit built-in does error?
If I enter pwd foo bar at the prompt of the bash shell, the foo bar part of the command line seems to be completely ignored.
If I enter exit 0 foo, I get bash: exit: too many arguments.
So pwd ignored ...
- 2,362
0
votes
1
answer
69
views
Bash Script Linux - combines a QUIET function with other functions without hiding some of them
#!/bin/bash
DefaultColor="\033[0m"
GREEN="\033[32m"
RED="\033[31m"
PURPLE="\033[35m"
YELLOW="\033[33m"
CYAN="\033[36m"
CmdOk="\033[...
- 3
0
votes
2
answers
48
views
Source file in bash to set prompt with ANSI colors
I have a file named .ps1, and I'm running source .ps1 in bash to try and set my prompt up with color. The contents of the .ps1 file are:
__prompt_command() {
local EXIT="$?"
local ...
5
votes
1
answer
388
views
locking scripts using flock - can same file descriptor be used concurrently?
Common method for preventing concurrent runs for a given script is utilizing flock as:
LOCK=/var/lock/my-lock
exec 9>>"$LOCK"
if ! flock --exclusive --nonblock 9; then
echo "...
- 71
0
votes
1
answer
97
views
Why does Firefox 'copy as cURL' not download any file not download anything here?
I tried to do this:
curl "https://imslp.org/wiki/Goldberg-Variationen%2C_BWV_988_(Bach%2C_Johann_Sebastian)" | perl -nle 'print "$1" while /<span id="num-of-ratings-[0-9]{6}...
- 53
6
votes
2
answers
331
views
suppress stderr when inputting a file to a variable
var="$(cat no-exists)"
var="$(< no-exists)"
give a similar output:
cat: no-exists: No such file or directory
bash: no-exists: No such file or directory
I'll describe the ...
- 347
0
votes
2
answers
88
views
Cleaning-up previous kernel RPMs after reboot
I have a few RHEL 8/9 boxes with a cron job that updates them automatically every week.
The reboots are done manually from time to time and I would like to write a script to simplify the removal of ...
- 1,613
4
votes
3
answers
222
views
Get Character Code for Character in File Name
Short version: I am at a bash command line. In some directory, I can ls various files and see their names. I would like to get something like the ASCII character code for each character in a file's ...
- 43
-4
votes
3
answers
150
views
-5
votes
1
answer
86
views
To have ., the source synonym, workable [closed]
The bash' command
source
has been modified in one of few ways:
alias
function overriding
or else
Then how can its synonym:
.
got being so too (problem is it's not letter) ?
- 87
0
votes
1
answer
36
views
How to set a bind -V variable from the bash command line, not ~/.inputrc? [duplicate]
$ bind -V | grep horiz
print-completions-horizontally is set to `off'
How do I set it to `on' from the bash command line?
I know how to set it in ~/.inputrc. That's not my question.
- 573
2
votes
1
answer
246
views
x2 sudo commands cannot be executed in terminal
I am running a Ubuntu system on my Radxa Zero 3E (single board computer)
Using its GPIO I am driving a 5V LED via an NPN transisitor. Everything works.
For switching it on I use gpioset $(gpiofind ...
- 323
4
votes
2
answers
292
views
Custom separator in ps
I have this integrated in a bash-script on an outdated Debian 10.
ps -axo "%p ;;; %a"
Works well, output is like
10161 ;;; [kworker/0:1-cgroup_destroy]
12173 ;;; [kworker/2:0-events]
12379 ;...
- 1,049
1
vote
3
answers
188
views
Execute bash commands one at a time
I have a list of bash commands that I'd like to execute one at a time. They could be in a file, or the terminal, or whatever is necessary. But I'd like to execute the first one then I'd check the ...
- 290
-9
votes
1
answer
111
views
"File name too long" when printing a long base64 string. Why?
Downloading an image and encoding it into base64:
curl -o output.jpg https://upload.wikimedia.org/wikipedia/commons/thumb/f/f6/USA-San_Jose-De_Anza_Hotel-3.jpg/500px-USA-San_Jose-De_Anza_Hotel-3.jpg
...
- 5,585
15
votes
2
answers
2k
views
Why does "seq 1000000 | tee /dev/stdout" produce more single-digit numbers than expected?
I'm in Linux and in Bash. I expect
seq 1000000 | tee /dev/stdout
to always output 9 numbers from 1 to 9 and their duplicates (18 in total). But when I do
seq 1000000 | tee /dev/stdout | grep -c '^[1-...
7
votes
1
answer
365
views
Cannot delete bash associative array element
Consider an associative array in bash (versions 5.2.15(1)-release and 5.2.21(1)-release):
declare -A ufs=(); ufs["one"]=1; ufs["two"]=2; ufs["three"]=3
printf '> %s\n' ...
- 128k
10
votes
5
answers
612
views
Grep with output of not the complete line
With grep I can filter lines.
But if the lines are pretty long it gets messy.
How can I only get "some chars around" my search-string?
f.txt
this is a red cat in the room
this is a blue ...
- 1,049
4
votes
4
answers
460
views
How can I find common prefixes in file names to group them?
I would like to be able to find all files in multiple directories whose file names start with the same string, but preferably not if that string is only one word or contains fewer than perhaps 5 ...
- 4,443
4
votes
1
answer
837
views
Why does bash need file descriptor duplicating?
I found out I don't totally understand how bash file descriptors work. I would like to have some guidance here.
I have a scenario where I need to read the content of a file, and for each line of the ...
- 718
1
vote
2
answers
106
views
Use numbered file descriptors with SSH
I need to pipe data through SSH to a command that reads stdin. The command needs to run with sudo so I need to be able enter the sudo password, too. Without ssh, I'd use numbered file descriptors like ...
- 434
0
votes
0
answers
29
views
can't remove items from the bash history using a while loop [duplicate]
I have a faulty command several times in my history and want to remove it with history -d <id_of_faulty_command>.
I can identify this via a --writeout (instead of the correct --write-out)
Now ...
- 287
2
votes
1
answer
214
views
cal or ncal - wrap more months?
Using cal and ncal, I know that I can display a certain number of months using various flags (for example, ncal -C -A 4 will show the current month and the 4 months after).
What I am trying, and so ...
- 148
-1
votes
2
answers
104
views
Unix folder has file named "-f". Standard `/bin/bash` tools do not recognized this (can not `rm`, `cat`, nor `stat` this). What to do? [duplicate]
Welcome to Termux
Docs: https://doc.termux.com
Community: https://community.termux.com
Working with packages:
- Search: pkg search <query>
- Install: pkg install <package>
- ...
- 23
14
votes
1
answer
643
views
How is bash autocompletion for Inkscape tied to dbus and how can I stop it?
Recently i noticed that when i try to "tab-tab" complete a filename for some gtk applications (i do not use gnome) i get dbus errors. for example:
$ inkscape pu (tab-tab, to complete the ...
- 953
12
votes
2
answers
1k
views
Why arithmetic syntax error in bash causes exit from the function?
I was debugging one script, and discovered unexpected behavour of handling arithmetic syntax error.
Normally, when error happens, script is just continuing execution.
#!/bin/bash
func2 () {
echo &...
- 1,209
4
votes
0
answers
232
views
Confused about SIGINT trap
I am confused about the processing of SIGINT and EXIT traps in Bash scripts.
I wrote this script to test:
#!/usr/bin/env bash
set -e
exit_trap() {
printf "In exit_trap \$?=$?\n"
exit 0
...
- 2,380
2
votes
1
answer
68
views
Make `set -o vi` vim cursor reflect editing mode when in `read`
I have a script read.sh:
read -ei "hello world"
eval $REPLY
Upon executing chmod +x read.sh and then running ./read.sh, I notice that pressing Esc followed by b or w jumps between the ...
- 25
0
votes
0
answers
38
views
Is there anything like `tail -f` but that can follow multiple files and show which file each line came from? [duplicate]
I'm trying to monitor multiple log files simultaneously, but when I use:
tail -f /var/log/app1.log /var/log/app2.log
I get mixed output and can't easily tell which file each line originated from. What ...
- 101
0
votes
0
answers
37
views
Bash replacement with new line [duplicate]
The command echo ${PATH//:/$'\n'} should replace colons with new lines. However, I am getting spaces. What am I doing wrong here?
- 1
2
votes
2
answers
342
views
How to add a prefix to all functions defined in a sourced shell script
I have a Bash script my.sh with commands such as:
jup () {
conda activate
cd
jupyter notebook
}
I source this file in .bash_profile with source my.sh and then I can run the command with ...
- 197
1
vote
2
answers
118
views
How to have bash logging ("set -x") only log the main command line (not split into pipelines)?
Consider this one-liner bash example:
$ (function test() { echo "testing a string" | grep "a" | sed 's/i/y/g'; }; set -x; test | grep "test" )
+ grep --color=auto test
+ ...
- 590
2
votes
3
answers
575
views
append iterator value to variable in for loop
I have a bash variable as such
HAP="$(echo ${d} | cut -f 7 -d '/' | sed 's/[A-Z,0-9]\+//' | sed 's/_//')"
that when is run as part of a script return either ref or hap. Now, I have another ...
- 323
0
votes
1
answer
66
views
command line access to bash directory stack [duplicate]
In the tcsh shell, the elements of the directory stack can be access on the command line using =<#>, e,g, =0 =1 .... and a sampled command like:
cp Something =1/
would copy file Something to ...
