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.
11,942
questions
-1
votes
2
answers
28
views
how to make a subshell a "program"
I want to ignore all pre-existing env variables, and echo just one, like this:
env -i (
export foo=bar;
env
)
and this would just print:
foo=bar
however, the construct of
env -i ()
doesn't ...
- 9,412
0
votes
1
answer
15
views
diffing two .env files
I have two env files, let's say x.env and y.env, the order of the variables is different, but the content could be the same but likely different.
Is there some tool I could use to diff the variables?
...
- 9,412
1
vote
1
answer
107
views
zsh: check exit code of pipeline of commands
I have long pipeline of commands in zsh script:
pv /dev/sda > sda.raw | sha256sum > sda.raw.sha256 | cut -c61-64 | read SHASUM
how can I check inside an if statement, that all commands exited ...
- 104
0
votes
0
answers
57
views
source command not loading all variables
I have file containing 1100 variables. Example,
LOGPATH=/some/path
VARIABLE2=someVALUE
while running source /path/to/file.properties
Only the first set number of variables are being loaded. Is there ...
- 3,674
-1
votes
2
answers
92
views
How to mark things I download automatically executable?
I spend a lot of time downloading things that I am going to execute, without a doubt, after having downloaded them. Out of the 900-ish files in my download folder right now, roughly a third is stuff ...
0
votes
1
answer
36
views
"mv" command with asterisk character ("*") executed using "ssh"
I am inexperienced with Linux, but I am learning every day.
I have this command.
ssh admin@$host mv repo/environments/qa/* /repo
Does this * character mean that EVERYTHING in the environments/qa ...
0
votes
1
answer
59
views
zsh: no such file or directory error even though the file exists [duplicate]
I'm getting an error while executing a binary that the binary cannot be found. I can see it using other commands.
>> ls -alh ...
- 3
0
votes
2
answers
37
views
Copy (Rsync) only files from subirectories
I'd be really happy about some help. Lets imagine a snapshot of a directory structure:
../test1/test6/test62.txt
../test1/test6/test65.txt
../test1/test6/test67.txt
../test1/test6/test69.txt
../test1/...
0
votes
3
answers
106
views
Figuring out the time until midnight, and output the result in a text file
How could I make lets say remaining time until tomorrow (midnight, also hours and minutes) and save that to a text file, like for example, "x hours and y minutes remaining until midnight"
...
- 3
0
votes
0
answers
64
views
Per-user cumulative CPU time across reboots
I have installed the process accounting package (acct) and recorded data.
Using sa --print-seconds --user-summary | grep "$USER", I get the process account summary for my user:
wjwrpoyob ...
- 376
-5
votes
0
answers
60
views
I need to sort files in recursive list, but there are some difficulties [closed]
I got some problems when I was doing the task:
Output the first four elements of a recursive list of file names and attributes in the lib0 directory containing the string "ra", sort the ...
0
votes
2
answers
44
views
Replace last nonblank line with a command output
I have a .env file like
PARAM1=val
PARAM2=val
I want to replace the last noblank line with another file content
So far I have something like below:
{ (sed -e :a -e '/^\n*$/{$d;N;ba' -e '}' local.env |...
- 103
0
votes
0
answers
30
views
How to find out which clipboard manager my system uses?
I am not sure if the clipboard manager works as that shell interpreter in the sense we select one and only one to use in an interactive login shell (i.e., the terminal). If so, I wonder how to find ...
- 235
1
vote
1
answer
26
views
How to redirect a command for a specific application
For example, the feh program can delete the currently viewed image, presumably using the rm command at some point. Let's say that instead of deleting the file, we want to run a trash script, say trash....
- 197
1
vote
4
answers
138
views
Read nth column iteratively in two large files, cut and paste side by side to create new nth file
I have two files with around 100,000 space-separated columns in each. I want to extract each with column of the two files, write to a separate file and do command 2.
Example for a file with two ...
- 37
1
vote
1
answer
833
views
What does mean `^(*.c|*.md)`
I am sorry if it is a potential obvious question, but I have no idea what ^() means in
ls ^(*.c|*.md)
On zsh, this argument expands to everything but *.c and *.md files.
What is ^?
What does mean ...
- 235
-1
votes
2
answers
77
views
Copy file from Server A to Server B
I have requirement to copy files from Server A to Server B
And then move the copied files Server A to Archive folder
I have written the script, but it takes the directory name differently.
Copying ...
0
votes
2
answers
33
views
How to extend piped command by contents of variable?
I would like to extend this line that calls /usr/bin/mplayer for recording an audio stream.
The referring script record.sh could get called multiple times in parallel and I need to know in which ...
- 11
4
votes
1
answer
15
views
Different behavior of `man` for root and user
Recently a user asked me for help and wrote:
"Why does invoking man /bin/find display gibberish?"
I answered that he was using man incorrectly by providing a path, that man was ...
- 143
-1
votes
0
answers
29
views
How does "." work exactly when the path directory is included and not included to execute a script file? [duplicate]
Suppose the following structure
/
snap
bin
notepadpp <--- file
If pwd returns /snap/bin/ to execute the script happens the following:
a: ./notepadpp the execution works
b: notepadpp the ...
- 1,488
0
votes
1
answer
20
views
Buffering follow + automatic pagination of output
I have a utility that continuously outputs live logs from a program. But it can be quite hard to read the logs lines as they scroll past me in the terminal. Ideally it should scroll to one full page, ...
- 101
0
votes
1
answer
86
views
Is listing files with ls dangerous as stated on gnu.org documentation?
Is listing files with ls dangerous?
If I run just ls command in a directory with unknown files, can something bad happen?
Can you show me examples how running ls command is dangerous as stated in this ...
- 11
0
votes
1
answer
47
views
How to copy a directory structure and rename a subdirectory in the destination
Given this directory structure
$ lsd --tree ...
- 111
1
vote
2
answers
43
views
Shell one-liner for batch renaming music albums folders according to regexp – “zsh: missing identifier after `+'”
My music library consists of folders named after the following pattern :
METAGENRE - Subgenre(s) - ARTIST - Album (year)
I want to switch the year and album "tags" in the folders' names for ...
- 79
-1
votes
1
answer
66
views
How does a terminal produce accurate colors?
Background
I am using terminals in various settings. Often the color output of programs is not correctly rendered on the screen.
The internet is full of recipes for fixing the colors for specific ...
- 231
1
vote
2
answers
93
views
How do I print out the file size in a shell script?
I'm trying to record the size of the compressed build file using Fastlane in my CICD pipeline. If I try this in the command line:
du -h fileName.ipa | awk '{print $1}'
it works fine. However, if I ...
- 11
0
votes
1
answer
89
views
zsh ignores zshrc most of the time (but not always)
So when I open a new terminal (kitty) my ~/.zshrc is sourced perfectly fine, oh-my-zsh works, plugins are loaded as well as the p10k theme. But if I, for example, simply run zsh (or tmux) I get a ...
- 11
0
votes
0
answers
27
views
CentOS 9 Stream SSH with PuTTy - multiline commands
I've been using CentOS versions 6, 7 and 8 for a long time. Finally, I started using CentOS 9 Stream version. It doesn't matter whether GNOME desktop version or server version (black screen), I ...
6
votes
3
answers
460
views
Pass result of find command as another command's multiple options
I have a CLI tool that can take an option with multiple values - The syntax is like this:
CLI -I path/to/file1 -I path/to/file2 ...
How can I pass the result of the find command to this CLI?
For ...
- 63
5
votes
3
answers
338
views
zsh -z test meaning of "+x"
I am new to zsh and have been a bash user for years.
In an example zsh script I see a test:
if [ ! -z ${ZSH_MOTD_CUSTOM+x} ]; then
In bash I would expect:
if [ ! -z "$ZSH_MOTD_CUSTOM" ]; ...
- 53
1
vote
2
answers
67
views
Is there a native linux command other than awk/sed/perl/python that can toggle pipe output on or off?
For example, suppose I define a variable:
DROP=
And I have a loop:
# highly compatible, streaming,
# line-wise parser for embedded device
# no awk or external dependency
while IFS= read -r line; do
...
- 913
0
votes
0
answers
26
views
how to rename last part of multiple file in linux [duplicate]
I want to rename to files from below format to below format . How can i rename last part ?
cheatsheetold1.gz.aux
cheatsheetold2.gz.log
cheatsheetold3.gz.out
cheatsheetold4.gz.pdf
cheatsheetold5.gz....
- 1
0
votes
1
answer
110
views
Is standard streams just variables?
When I run command, e.g. test -l --hello check:
shell save the command to variables, $0="test", $1="-l", $2="--hello" and $3="check"
shell execute ...
- 27
-1
votes
2
answers
95
views
Why pipe keep sudo and redirection not? [duplicate]
Pipe (|) and redirections (<, <<, >, >>) both using standard streams (stdin, stdout, stderr), but although only pipe can keep sudo privileges, why?
Works:
sudo echo "hello" ...
- 27
1
vote
1
answer
44
views
Converting a tcsh alias into zsh
I had a tcsh alias as follows:
alias cdd 'cd `dirname \!*`'
I use this to change the directory to the one containing a certain file.
For instance,
cdd /Users/myself/Document/Folder/File.pdf
would ...
- 13
0
votes
1
answer
38
views
How do I determine the PID of the shell running a given pts/tty?
There are many ways to obtain the PTS associated with a given process - such as using the tty command or resolving /proc/self/fd/0 (assuming it's open and not redirected) - but what about the inverse? ...
- 958
0
votes
3
answers
75
views
Does `return 0` equal `true` (in sourced script to shell's environment)?
I am working on a highly portable script that users shall source to their shells, forcing me to use POSIX scripting.
There are many useful functions in the script, one of them is special though, as ...
- 27.8k
0
votes
1
answer
47
views
mkfs.xfs completely ignoring "|more" redirect
trying to install gentoo linux and can't format the drive with xfs because when I run mkfs.xfs /dev/sda3 it throws an error and then displays help, but the help is so big that it takes up the entire ...
- 1
0
votes
1
answer
69
views
Check if two IP addresses are in a range
Using bash or perl on a minimal installed Linux, I am trying to validate two IP addresses if there are in a range.
I came across a bash script that works well, but the fact that it prints all the IP ...
- 1,524
0
votes
2
answers
129
views
commands ran from Makefile are buffered, and don't print output imediately
when I run following command in shell, I see the rsync output real-time, as the files are being transfered:
rsync --out-format="%n" --info=name1,del2 -rt /foo bar | sed '\@/mmc/@d' | grcat /...
- 104
-2
votes
3
answers
96
views
sed: -e expression #1, char 101: unterminated `s' command
can someone suggest me what is going wrong here -
sed -i "s|##CONNECTION_DETAILS##|${CONNECTION_DETAILS}|g" dep.yaml.
The value of CONNECTION_DETAILS is in encoded form:
...
- 3
0
votes
2
answers
38
views
Getting only used memory from free command every few seconds
It was explained e.g. here:
Get separate used memory info from free -m command
how to cut the output of free command. But I want to do this every few seconds and log it to a file. So I tried:
free -g -...
0
votes
0
answers
25
views
Sending files using slack-api
curl -F file=@"/home/siva/Downloads/heap2.hprof.gz" -F channels="xxxxxxxxxxxxxxxx" -H "Authorization: Bearer xxxxxxxxxxxxx" https://slack.com/api/files.upload
My file ...
25
votes
3
answers
5k
views
Is it now safe to parse the output of GNU ls?
The accepted wisdom for the past few decades has been that it is never a good idea to parse the output of ls ([1],[2]). For example, if I want to save a file's modification date along with its name ...
- 235k
1
vote
2
answers
145
views
How to find files created one hours before?
I have the folder, the files will comning hourly daily in here. After that, i want to copy only files, which created date one hours before to other folder.
For example: Currently datetime is 9:20:00AM,...
- 113
0
votes
2
answers
39
views
How do you find the path from where a cli is called from?
Let's say I'm building a CLI app. Let's say it's written in Python. For simplicity's sake, let's say this app echoes the given dir or file canonical path.
The user calls myApp ..
How can my app know ...
- 153
0
votes
3
answers
92
views
Extract UTC time and find difference
I have a file with the following sample records for buy and sell events
Buy at time=Thu Aug 03 2023 14:13:08 GMT+0200 (Central European Summer Time)
Sell-at time=Thu Aug 03 2023 14:53:02 GMT+0200 (...
- 91
0
votes
1
answer
37
views
Why does Unix background process termination line not print right after termination?
So as an example if I run:
sleep 1 & sleep 2 & sleep 3
I will immediately get the process IDs e.g.
[1] ...
[2] ...
and then the shell freezes until the sleep 3 finishes running and then ...
0
votes
1
answer
62
views
Path of ${1#*=}?
What does pluginPath="${1#*=} signify as per path in linux.
It is from openfoam's parafoam from directory by the way \\wsl.localhost\Ubuntu\usr\lib\openfoam\openfoam2306\bin
was trying to change ...
- 1
0
votes
0
answers
31
views
Bash script or the like to erase env values that host secrets once used to initialized app in a kubernetes container
I have a flask app that runs in a kube cluster. It does all the right things by using kube secrets to set the env values required to initialize the application. There are some env values I suspect ...
- 101