Questions tagged [dash]
The Dash shell, a POSIX-compliant derivative of the Almquist shell used as /bin/sh in Debian, Ubuntu and other Linux distributions
161
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ffmpeg dash playback stream ends to early
I am trying to play back a dash manifest using ffmpeg but I keep running into the issue of ffmpeg ending with the error
[http @ 0x671e580] Stream ends prematurely at 2250, should be ...
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1
vote
1
answer
46
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Bash for every x files create sub folder and move files there
I am looking for an alternative dash command I can use
as I am trying to execute the code from within python
and due to the fact that the sub folder has 100's of files I am am trying to group into ...
- 21
0
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0
answers
21
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how to close file descriptor bigger then 9 by dash in shell script
I want launch a shell script in code called system("sh example.sh"), and close all file descriptors like this:
for fd in $(ls /proc/$$/fd); do
case "$fd" in
0|1|2)
;;...
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0
votes
2
answers
26
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Sourcing file in dash with . file gives "not found" error
I'm trying to source (bash-parlance) a file in dash using . file as specified by the man page:
. file
The commands in the specified file are read and executed by the
shell.
But I ...
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votes
0
answers
71
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What parts of dash are not part of the POSIX standard?
I know that dash adheres quite closely to the POSIX standard, but I know that it's not 100.00% strict POSIX without any extras. The shell that comes closest/adheres exactly to the POSIX standard is as ...
1
vote
1
answer
52
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SHELLOPTS equivalent for /bin/dash
I have to run a number of shell scripts that are defined by a third party. So I cannot (or would prefer not to) change their content or which shell (bash vs. dash) they are using. They may or may not ...
- 133
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votes
1
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41
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Incorrect order of commands in "Command Substitution" (Bash/Dash)
Why is it that when you run the substitution commands, the order of execution is broken, as in the example below. First the chmod command was executed, then echo 1 and echo 2?
echo $(echo 1; echo 2; ...
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49
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Secure transfer of arguments to a program (dash/bash)
Transfer via stdin
#!/bin/dash
echo 'password' | program -
Transfer via stdin using an intermediate variable
var_pass=$(echo 'password')
echo $var_pass | program -
unset var_pass
Transfer via ...
- 127
0
votes
1
answer
55
views
Proper way to wrap dash using rlwrap
On Ubuntu, I have set alias sh='rlwrap --complete-filenames sh' to get readline keybindings and filename completion when using the dash shell (on my computer, sh is /usr/bin/sh, which is a symbolic ...
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-1
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3
answers
74
views
Changing the place operator in a csv file
I've been editing a CSV file so I can import it into postgres. At this point I want to change the operator from column 5 to the left side of the column when the value is negative"-". When it ...
0
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3
answers
69
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find/detect file name goups
On fs i have files like:
PREFIX_GROUPNAME_OTHERNAMES[.txt|.*]
eg:
A_ABC_A.txt
A_ABC_B.txt
A_ABC_C.txt
A_XYZ_A.txt
A_XYZ_B.txt
A_XYZ_C.txt
For some futher tasks i want to get the group names.
$# ...
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2
votes
0
answers
42
views
Can't grep or word count the output of jobs command in dash
This is what I tested in Arch's dash shell and FreeBSD's default sh shell, the results are the same.
$ sleep 100 &
$ jobs
[1] + Running sleep 100
$ jobs | wc
0 0 ...
- 21
-1
votes
1
answer
83
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purpose of dashes in `wget -qO- https://get.speedify.com | bash -`
In this command:
wget -qO- https://get.speedify.com | bash -
Source: https://support.speedify.com/article/562-install-speedify-linux
...the first -q is the option for "quiet" mode. What is ...
- 1,378
1
vote
1
answer
274
views
ssh: force different shell for non-interactive command execution
how can I force specific shell to be used for non-interactive command execution via ssh on remote server?
My default shell on the remote server is zsh, but I need to execute given command using /bin/...
- 422
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votes
1
answer
470
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/bin/sh: wildcard expansion does not work in script
I am using dash as /bin/sh. In my script, I have following line:
SSH_AUTH_SOCK=/tmp/ssh-????????????/agent.*
Which is supposed to match file /tmp/ssh-abcdefghijkl/agent.1234. Even when the file ...
- 422
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votes
2
answers
111
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How to execute a one-line posix dash command within dash script to enable coredump?
For unrelated purposes I am forced to produce a script that only works with posix sh.
Within my script I have checked if the system allows the creation of coredumps, then if the limit is set to 0 I ...
3
votes
1
answer
55
views
dash and local keyword not resetting shell
dash shell (unlike bash and busybox ash implementation where both examples print foo: '') takes value of previously
defined variable, i.e. guarding with local does not work:
$ foo=ee; bar() { local ...
- 1,339
-1
votes
1
answer
110
views
Having an interactive shell experience but running everything through dash
So i'm starting to get addicted to POSIX standards and simplicity yet i hate not having autocomplete using the arrows to go through characters and i want a cool shell prompt.
so is there anyway that i ...
- 113
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0
answers
64
views
Why integer division is faster than bitwise shift in shell?
I'm comparing performance of bash and dash (default sh in Xubuntu 18.04).
I expect sh to be faster than bash
I expect bitwise shift to be faster than division operator.
However, I'm getting ...
1
vote
2
answers
69
views
Can't delete multiple files with spaces on name with rm
I'm working on a deploy script for my dotfiles, they are stored on a Git bare repository, from which i git checkout it's files into my home directory, in order to seamlessy do it without thousands of ...
- 631
-4
votes
1
answer
604
views
How to printf ascii characters with hex or dec inside /bin/sh -c '...'?
/bin/sh would be dash
what is the correct syntax for printf to display certain ascii character using hex or dex code in dash?
let's say i want to printf a dollar sign ($). which hex or dec code should ...
user476578
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1
answer
122
views
Global Variables across scripts [duplicate]
Why is lets say HOME recognized by all my scripts but my variable DMENU isn't?
I export it in my bspwmrc file which is executed at start up.Also had it in my zshrc.
Why do this?
DMENU="-h 27 -z ...
- 23
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votes
1
answer
73
views
su not working inside arch-chroot with dash shell
When i try to do the following inside a dash script:
#!/bin/dash
arch-chroot /mnt /bin/dash <<- EOF
su myuser
whoami
EOF
It simply logs the "root", but when i try to do it ...
- 631
10
votes
2
answers
1k
views
Shell script returns 0 exit_status despite syntax error
Consider this script:
#!/bin/sh
foo=1
if [[ ! -z $foo ]]; then
echo abc
fi
It's using the Bash syntax [[ ... ]] which doesn't work (as expected) when I run it with the default shell on Ubuntu (...
- 113
4
votes
2
answers
275
views
bash -e and && evaluation inside functions
I'm puzzled by bash (and dash) behavior when -e option is set.
Simple example:
#!/bin/bash -e
func() {
false && true
}
false && true
echo "1"
func
echo "2"
...
- 43
1
vote
2
answers
162
views
/bin/sh evaluates string while Bash does not
When running the script below, I get two different outputs, depending on whether or not the shell used is sh or bash:
regex(){
echo 's/\(.* \)\(!\{0,1\}\)has(/\1\2MOCK_has(/g'
}
replace_builtins(...
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1
vote
1
answer
58
views
Can't use variables while feeding commands to bash through stdin
I need to run a small shell script using C popen call (which calls sh -c '<command>'). I can't get my script to work. I isolated the issue to this snippet:
#!/bin/bash
sh -c 'bash -xev -s <&...
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3
votes
2
answers
266
views
Why does printf byte formatting fail when executed under `dash`?
The ASCII hex code for a zero is 0x30. Hence, you can print a zero by doing printf '\x30', and it will print a zero.
If you put this into a shell script called myScript.sh, and then execute ./myScript....
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-1
votes
1
answer
195
views
variable regex test in dash?
I got plenty possible variables in a form of [a-z][0-9], eg 1 letter and 1 number.
Is there a way to test them in dash? Something like:
myvar=o7
if [ $myvar=o[0-4] ]; then
"do this"
elif [ $...
user434951
0
votes
1
answer
76
views
dash: How can I quote the arguments ala "${(q+@)@}" in zsh?
I want to quote the arguments in dash (or sh, or even bash if that's not possible). I can do that with "${(q+@)@}" in zsh, such that reval <sth> ... is the same as just typing in <...
- 1,287
0
votes
1
answer
130
views
cmd nested in backticks processed from sudo?
Are nested `commands` using (deprecated) backticks executed with root permissions (from sudo command line) while command substitution $(...) is not?
for example
sudo mount `blkid -u /dev/sda1` ...
...
- 519
2
votes
1
answer
92
views
emulate zsh multios in dash (multiple redirections)
in zsh, when the option multios is enabled, I can pipe output to two different processes, ie:
cat /dev/sda > sda.img | sha256sum > sda.img.sha256
How could I achieve the same in dash, ie /bin/...
- 422
2
votes
0
answers
178
views
Trap on DEBUG signal for the ash and dash shells?
With the bash shell, you can install a trap on the synthetic DEBUG signal. This is useful and will execute your function or bit of code on every shell command.
Not so in ash or dash.
$ trap 'echo hi' ...
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2
votes
1
answer
431
views
Do all POSIX shells implement arithmetic expansion $((...)) in the same way? [duplicate]
I'm trying to write a shell script which should work under any POSIX shell, and I found what seems to be an odd quirk of dash. I'm wondering whether this is something I can rely on working under other ...
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votes
1
answer
32
views
dash: echo args exactly with no processing
I want to do sth like zsh's print -r -- ... which just echoes the arguments without changing them at all.
printf -- still interprets directives.
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votes
2
answers
95
views
execlp() system call
I want to call the ulimit shell command through a C program. right now, I have:
execlp("ulimit", "ulimit", "-u", "%d", ulimit_a);
It compiles fine, but does not actually edit the user-id max ...
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7
votes
1
answer
5k
views
Error sh: 1: read: arg count
I want to simply wait for the user to acknowledge a message by pressing Return. In bash, I am able to call
$ read
$
However, in sh (dash in my case), I get
$ read
sh: 1: read: arg count
$
It ...
- 1,964
1
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0
answers
22
views
length of the command line buffer [duplicate]
Which's the length of the command line buffer, per shell... and per operating system (if applicable)?
Mostly interested in contemporary versions of Dash and Bash and Debian and macOS, but if anyone ...
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votes
2
answers
851
views
Why does SIGTERM work to terminate bash but not ash or dash?
Comparing bash, ash and dash, only bash can be terminated by SIGTERM
kill -TERM <pid>
For ash and bash, I need SIGHUP or SIGKILL
kill -HUP <pid>
kill -KILL <pid>
What's the ...
- 1,964
0
votes
1
answer
460
views
Dash non-interactive non-login rc file
Does dash have a non-interactive non-login rc file? I've read the man page, which recommends .profile for login shells and $ENV environment variable for interactive shells.
Is there anything that ...
- 454
1
vote
1
answer
497
views
How to kill all background jobs in dash?
Simply kill $( jobs -p ) not work in dash.
For example in dash:
$ sleep 999 &
$ kill $(jobs -p)
dash: 2: kill: Usage: kill [-s sigspec | -signum | -sigspec] [pid | job]... or
kill -l [...
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2
votes
1
answer
137
views
No /var/lib/dpkg/info/dash.preinst in Buster
In https://wiki.debian.org/Multistrap#Steps_for_Squeeze_and_later, it's required to run the following command in chroot environment:
/var/lib/dpkg/info/dash.preinst install
This command runs in ...
- 1,947
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votes
2
answers
1k
views
Are shells allowed to ignore NUL bytes in scripts?
Because that's what some of them are doing.
> echo echo Hallo, Baby! | iconv -f utf-8 -t utf-16le > /tmp/hallo
> chmod 755 /tmp/hallo
> dash /tmp/hallo
Hallo, Baby!
> bash /tmp/hallo
/...
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votes
2
answers
735
views
Is there a way to make the local command work portably to dash ksh bash and zsh?
In dash (and in bash zsh and some other shells) the command local works to make a variable scope limited to that function (and descendants in some cases). That enable the possibility of making a ...
- 38.8k
4
votes
2
answers
328
views
Why the parent shell here-document not work for sub-command in dash but bash work?
I'm run on debian stretch, all below commands(dash and bash) is input to bash.
The whoami seem never run as the user test in dash as in below codes.
$ sudo dash << 'end'
> su test
> ...
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3
votes
1
answer
519
views
Putting "$@" in a local variable in dash
I have a Bash function that does some string manipulation on its arguments as a whole ("$@") by putting it in a local variable, something like this:
#!/bin/sh
my_func() {
local args="$@"
...
- 212
0
votes
3
answers
3k
views
I would like to check if a file name matches a certain pattern
I would like to check if a file name matches a certain pattern start with an alphanumeric character ([a-zA-Z0-9]) and will only contain alpha-numeric characters plus '.', '-' and '_' characters.
...
8
votes
2
answers
576
views
dash not expanding glob wildcards in chroot
I'm working with a copy of Raspbian, installed with pi-gen. Pi-gen runs in a Docker container with a volume for the filesystem, running debootstrap and custom scripts inside a chroot to the volume.
I'...
- 261
6
votes
3
answers
2k
views
Why does ''cat "${1:-/dev/stdin} | ... &>/dev/null'' work in bash but not dash?
Script:
#!/bin/sh
#
# reads stdin/file and copies it to clipboard
# clears it after 30s
#
cat "${1:-/dev/stdin}" | timeout 30 xclip -i -selection clipboard -r -verbose &>/dev/null &
I ...
- 71
7
votes
3
answers
1k
views
Shell builtin `printf` line limit?
The /usr/bin/printf util argument list length is limited to the shell's maximum command line length, (i.e. getconf ARG_MAX, on my system that'd be 2097152); example:
# try using a list that's way too ...
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