Questions tagged [bash]
Questions specific to GNU’s Bourne Again SHell, as opposed to other Bourne/POSIX shells. For questions about Unix shells in general, use the /shell tag instead. For shell scripts with errors/syntax errors, please check them with the shellcheck program (or in the web shellcheck server at https://shellcheck.net) before posting here.
26,540 questions
2votes
1answer
48views
Using mapfile on the output of another command [duplicate]
I want to edit a file before feeding it into an array. The data file contains: Line 1 Line 2 Line 3 If I read it with mapfile -t direct < data I obtain a 3-element direct array But I pipe the ...
- 9,248
-4votes
0answers
49views
Creating in Linux files in GB or MB range by various random size by read a file [closed]
In Linux in Bash i have this script (thanks to Ed Morton) . $ cat ./tst.sh #!/usr/bin/env bash while read -r idx sfx size; do echo fallocate "file${idx}.${sfx}" "$size" done &...
- 533
0votes
1answer
47views
How to make bash not set the underscore _ environment variable?
How to make bash not set the underscrore _ variable for the processes that it's starting? Explanation of what it is if you haven't encountered it before: If you launch env from bash, you'll see the ...
- 1,507
0votes
0answers
38views
Understanding `bash` options -Ee
In a larger script I have trap -p echo "settings: [$-], command: [$*]" "$@" echo "return code $?" and I get the output trap -- '_shunit_cleanup EXIT' EXIT trap --...
- 1,030
6votes
4answers
518views
Using curly braces to process colon-separated variables
If we do: VAR=100:200:300:400 We can do: echo ${VAR%%:*} 100 and echo ${VAR##*:} 400 Are there any equivalents I could use to get the values of 200 and 300? For instance, a way to get only what's ...
- 2,210
-2votes
1answer
108views
Creating in Linux files in GB or MB range by various size by read a file [closed]
In Linux with Bash, there is the File numbers_in_one_line. In this file there is only one line with several numbers, all separated by spaces. These numbers are the value in bytes for creating files ...
- 533
-1votes
2answers
79views
Counting unique IP addresses per hour in existing log files
I am trying to determine the number of unique web visitors to my website each hour. The log files (access*.log) contain many lines looking similar to this. 192.168.211.85 - - [29/Sep/2024:10:17:02 -...
- 307
0votes
1answer
44views
Where to set XDG_RUNTIME_DIR per user?
So I ran into the following interesting problem: I tried to define XDG_RUNTIME_DIR in my .bashrc as follows: export XDG_RUNTIME_DIR=$MY_HOME/.local/share After doing this I noticed my pactl cli ...
- 117
0votes
1answer
68views
bash - list of breaking change
I know bash tries very hard to keep new versions compatible with previous ones. However they sometime introduced (minor, but still) breaking changes: for exemple when we could no longer have : { foo }...
- 6,570
2votes
1answer
52views
Why can't I have a single quote in a bash associative array index when testing with `test -v` [duplicate]
When I run the following code declare -A X # get an associative array index="a'b" # a somewhat weird index X[$index]="this is set" echo "<<${X[$index]}>>" if ...
- 1,030
14votes
1answer
3kviews
Why does cd '' succeed in bash?
Maybe I'm missing it, but I don't find it documented that cd '' should succeed. Since there is no directory with the name '', it seems obvious that it should fail. For example, mydir= cd -- "$...
- 1,089
0votes
2answers
80views
How does `*\ *` work in bash?
There is an answer from SuperUser, which renames filenames containing whitespace: for f in *\ *; do mv "$f" "${f// /_}"; done The part I don't understand is *\ *. The author wrote ...
- 135
2votes
1answer
184views
Using Here-Document as password Input for ssh
First, I do know this is a security risk. I do know about ssh keys and sshpass. This belongs to a fun project. I wondered if a bash Here-Document could be used as a password input for ssh. I ...
-3votes
1answer
96views
bash -n is a not documented in manpages or info documents [closed]
Even though bash -n is a valid and widely used option, some manpages don't clearly document it in the bash options section, even though it is implemented. It's also not in the GNU Bash Reference ...
- 1,166
5votes
6answers
1kviews
Why can't I merge folders by renaming one of them?
Try to run this mv -- "foldername...__" "foldername..." This will move folder foldername...__ under the folder foldername... instead of renaming it. Why? Note that foldername... ...
- 308
