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0 votes

1 answers

70 views

Understanding `bash` options -Ee

In a larger script I have ```bash trap -p echo "settings: [$-], command: [$*]" "$@" echo "return code $?" ``` and I get the output ``` trap -- '_shunit_cleanup EXIT' EXIT trap -- '_shunit_cleanup INT' SIGINT trap -- '_shunit_cleanup TERM' SIGTERM settings: [ehuBET], command: [false VAR2 VAR1] return...

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 -- '_shunit_cleanup INT' SIGINT
trap -- '_shunit_cleanup TERM' SIGTERM
settings: [ehuBET], command: [false VAR2 VAR1]
return code 1

We see that the command false is run and we see that it exits with code 1. But we also have set -e from which I would expect that we should never see the line return code 1, because as soon as false exists with 1 the whole script should stop. Afaict the traps are not relevant. I tried to reproduce the situation with a minimal example, but in all smaller tests, the immediate exit due to -e does happen. Which setting or options should I look at to explain the above? **More background and findings:** The problematic code is called as part of a shunit2 test from within a testing function. If I call that same testing function directly, without invoking it through shunit2, the problem is gone. But to confirm: my confusion lies mostly in the facts which can be seen from the output above alone: set -e seems to be on, false is called but instead of exiting right away, the next line of code (echo) is executed anyway.

Harald (1030 rep)

Apr 27, 2025, 07:22 AM • Last activity: Jun 12, 2025, 02:44 PM

4 votes

1 answers

134 views

Bash extglob with ignored pattern

bash wildcards shopt globstar

Suppose I have these files: ``` foo/bar/baz/test.js foo/bar/baz/test.min.js ``` If I run: ```sh shopt -s globstar shopt -s extglob echo foo/bar/**/*!(.min).js ``` ...that will nonetheless match the `test.min.js` file. How do I ignore it?

Suppose I have these files:

foo/bar/baz/test.js
foo/bar/baz/test.min.js

If I run:

shopt -s globstar
shopt -s extglob
echo foo/bar/**/*!(.min).js

...that will nonetheless match the test.min.js file. How do I ignore it?

lonix (1965 rep)

Dec 13, 2024, 11:01 AM • Last activity: Jan 6, 2025, 01:58 PM

0 votes

1 answers

140 views

Using shopt extdebug inside .bashenv

bash windows-subsystem-for-linux trap shopt

I'm using Ubuntu within Windows Subsystem for Linux. With the approach suggested by this [answer](https://unix.stackexchange.com/a/771542/305710) I can run code when a new non-interactive shell is started: ```shell $ cat ~/.bashenv if [[ $- != *i* ]]; then echo foo fi $ export BASH_ENV=~/.bashenv $...

$ cat ~/.bashenv
if [[ $- != *i* ]]; then
  echo foo
fi
$ export BASH_ENV=~/.bashenv
$ bash -c 'echo bar'
foo
bar

Now I am looking to setup a trap function with shopt extdebug enabled. I tried something like this:

$ cat ~/.bashenv
#!/bin/bash
say_foo() {
  echo "foo"
}
set -T
trap 'say_foo' DEBUG
shopt -s extdebug
$ export BASH_ENV=~/.bashenv
$ bash -c 'echo bar'
foo
bash: /usr/share/bashdb/bashdb-main.inc: No such file or directory
bash: warning: cannot start debugger; debugging mode disabled
foo
bar

Is there any way to fix this? --- A shorter way of reproducing the same issue:

$ bash --debugger -c 'echo hello'
bash: /usr/share/bashdb/bashdb-main.inc: No such file or directory
bash: warning: cannot start debugger; debugging mode disabled
hello

(Running an in-line bash script with --debugger is the same as setting extdebug in a file read via $BASH_ENV.)

Foo (242 rep)

Mar 14, 2024, 04:35 PM • Last activity: Mar 19, 2024, 11:02 PM

1 votes

1 answers

228 views

Expand a list of files including globs, which are defined in a file

bash wildcards shopt

I'm using bash. Suppose I have a file named `filelist`, which contains a list of files: ``` stuff/**/*.csv # to keep it simple (without loops), assume just one entry #*.txt #foo.md #bar.bin ``` And I want to expand that: ```sh ls $(cat filelist) ``` I get: > ls: cannot access 'stuff/**/*.csv': No su...

I'm using bash. Suppose I have a file named filelist, which contains a list of files:

stuff/**/*.csv     # to keep it simple (without loops), assume just one entry
#*.txt
#foo.md
#bar.bin

And I want to expand that:

ls $(cat filelist)

I get: > ls: cannot access 'stuff/**/*.csv': No such file or directory What I want is to expand that into a list of files which I can pipe to my main app for processing. How can I do that?

lonix (1965 rep)

Dec 30, 2023, 06:28 AM • Last activity: Dec 30, 2023, 02:41 PM

2 votes

0 answers

80 views

Pattern list in bash extglob containing a / and a |

bash wildcards pattern-matching shopt

Here is a transcript of commands (and their output) that explains my problem: ``` /tmp/example $ shopt -s cdspell on checkwinsize on cmdhist on complete_fullquote on direxpand on dirspell on expand_aliases on extglob on extquote on failglob on force_fignore on globstar on histappend on interactive_c...

Here is a transcript of commands (and their output) that explains my problem:

/tmp/example $ shopt -s
cdspell         on
checkwinsize    on
cmdhist         on
complete_fullquote      on
direxpand       on
dirspell        on
expand_aliases  on
extglob         on
extquote        on
failglob        on
force_fignore   on
globstar        on
histappend      on
interactive_comments    on
login_shell     on
nocaseglob      on
nullglob        on
progcomp        on
promptvars      on
sourcepath      on

/tmp/example $ ls -R
.:
prefix_bar  prefix_foo

./prefix_bar:
test.c

./prefix_foo:
baz  test.c

./prefix_foo/baz:
test.c

/tmp/example $ ls prefix_@(foo/baz|bar)/test.c
prefix_bar/test.c

/tmp/example $ ls @(prefix_foo/baz|prefix_bar)/test.c
prefix_bar/test.c

Question: Why does bash ignore the foo/baz or the pattern_foo/baz portion of the pattern-list? For the record, I looked around before posting this question and the question closest to what I am about to ask is https://unix.stackexchange.com/questions/548745/bash-extglob-should-the-order-of-patterns-in-a-pattern-list-matter (and it does not answer my question).

Happy Green Kid Naps (121 rep)

Oct 6, 2023, 11:10 PM

114 votes

7 answers

29844 views

Set and Shopt - Why Two?

bash settings shopt

`set` and `shopt` are both shell builtins that control various options. I often forget which options are set by which command, and which option sets/unsets (`set -o/+o`, `shopt -s/-u`). Why are there two different commands that seemingly do the same thing (and have different arguments to do so)? Is...

                                  set and shopt are both shell builtins that control various options.  I often forget which options are set by which command, and which option sets/unsets (set -o/+o, shopt -s/-u). Why are there two different commands that seemingly do the same thing (and have different arguments to do so)? Is there any easy way/mnemonic to remember which options go with which command?
                                

Kevin (41635 rep)

Feb 22, 2012, 04:17 PM • Last activity: Jun 2, 2023, 07:40 AM

7 votes

5 answers

4674 views

Check for bash options

bash shopt

I have a function and would like to use the `pipefail` option inside. But I don't want to simply `set -o pipefail`, because I fear that another part of the script may not expect `pipefail` to be set. Of course I could do `set +o pipefail` afterwards, but in case `pipefail` was set outside of my func...

                                  I have a function and would like to use the pipefail option inside. But I don't want to simply set -o pipefail, because I fear that another part of the script may not expect pipefail to be set. Of course I could do set +o pipefail afterwards, but in case pipefail was set outside of my function, this may introduce unexpected behavior as well.

Of course I could use the exit code of false | true as a measure, if pipefail is set, but this seems a little bit dirty.

Is there a more general (and maybe canonical?) way to check the set bash options?

red_trumpet (345 rep)

Nov 22, 2017, 08:26 AM • Last activity: Jun 21, 2022, 07:48 PM

59 votes

5 answers

31072 views

How can I list Bash's options for the current shell?

bash shopt

The Bash interpreter itself has options. For example, those mentioned on lines 22-23 of [Bash's man page](https://man7.org/linux/man-pages/man1/bash.1.html#OPTIONS): > OPTIONS > All of the single-character shell options documented in the description of the set builtin command can be used as options...

                                  The Bash interpreter itself has options.

For example, those mentioned on lines 22-23 of [Bash's man page](https://man7.org/linux/man-pages/man1/bash.1.html#OPTIONS) :

>   OPTIONS  
>   All of the  single-character shell options documented in the description of the set builtin command can be used as options when the shell is invoked.   In addition, bash interprets the following options when it is invoked:  
    -c ...  
    -i ...  
    -l ...  
    -r ...  


I've used a few search patterns in Bash's man page like:

* /^\s*set
* /list

Is it possible to print a list of these settings that are applied to the current shell?

                                

the_velour_fog (12760 rep)

Jun 17, 2015, 07:04 AM • Last activity: May 20, 2022, 05:03 PM

10 votes

1 answers

764 views

Setting bash options in a compound command

bash shopt

I have found that setting the `extglob` shell option only within a compound compound results in failure of subsequent extended globs. Are shell options required to be set outside of compound commands? I did not see an indication of such a requirement in the Bash man pages. As an example, the followi...

                                  I have found that setting the extglob shell option only within a compound compound results in failure of subsequent extended globs. Are shell options required to be set outside of compound commands? I did not see an indication of such a requirement in the Bash man pages.

As an example, the following script works fine (prints a.0  a.1):

    #!/bin/bash
    touch a.0   a.1 \
          a.b.0 a.b.1
    shopt -s extglob
    ls "a."!(b*)

However, if the last two lines are executed as a compound command, the script fails with the following error:

    syntax error near unexpected token `('
    `    ls "a."!(b*)'

This was tested using Bash versions from 4.2 to 4.4 and with a variety of compound commands :

(1) conditional -- if

    #!/bin/bash
    touch a.0   a.1 \
          a.b.0 a.b.1
    if true; then
        shopt -s extglob
        ls "a."!(b*)
    fi

(2) braces -- { }

    #!/bin/bash
    touch a.0   a.1 \
          a.b.0 a.b.1
    {
        shopt -s extglob
        ls "a."!(b*)
    }

(3) subshell -- ( ):

    #!/bin/bash
    touch a.0   a.1 \
          a.b.0 a.b.1
    (
        shopt -s extglob
        ls "a."!(b*)
    )

In all cases, if the shopt is moved outside the compound command, the script succeeds.
                                

user001 (3808 rep)

Jun 2, 2019, 10:13 PM • Last activity: Nov 16, 2021, 11:37 AM

5 votes

1 answers

1872 views

Are there any caveats in using shopt -s autocd?

bash shell-script cd-command shell-builtin shopt

I have recently discovered the feature `shopt -s autocd`: autocd If set, a command name that is the name of a directory is executed as if it were the argument to the cd command. This op‐ tion is only used by interactive shells. At first glance it seems helpful but I am not an expert Bash user and I...

                                  I have recently discovered the feature shopt -s autocd:

              autocd  If  set,  a command name that is the name
                      of a directory is executed as if it  were
                      the argument to the cd command.  This op‐
                      tion is only used by interactive shells.

At first glance it seems helpful but I am not an expert Bash user and I wonder if it may be a mistake to use it.

Are there any potential dangers to setting shopt -s autocd? I am especially interested in terms of scripting and conflicts with other applications or configurations.

mgarort (465 rep)

Apr 26, 2021, 01:24 PM • Last activity: Apr 26, 2021, 04:17 PM

1 votes

0 answers

205 views

Usage of gnu_errfmt option in bash

bash shopt

I readed [GNU/Bash document][1] but i can't understand or find any realworld usage example. **gnu_errfmt** > If set, shell error messages are written in the standard GNU error > message format. **When i try:** ``` └─$ shopt -u gnu_errfmt └─$ no_command -bash: no_command: command not found └─$ shopt...

I readed GNU/Bash document but i can't understand or find any realworld usage example. **gnu_errfmt** > If set, shell error messages are written in the standard GNU error > message format. **When i try:**

└─$ shopt -u gnu_errfmt
└─$ no_command
-bash: no_command: command not found
└─$ shopt -s gnu_errfmt
└─$ no_command
-bash: no_command: command not found

May you please give me real usage purpose and example.

testter (1510 rep)

Mar 31, 2021, 02:28 PM

0 votes

1 answers

921 views

What does shopt histreedit do?

command-history shopt

`shopt histreedit` is supposed to allow the user to re-edit a failed history substitution. How can a history substitution fail? How is `histreedit` different from `histverify`?

                                  shopt histreedit is supposed to allow the user to re-edit a failed history substitution.

How can a history substitution fail?

How is histreedit different from histverify?

EmmaV (4359 rep)

Mar 27, 2021, 05:34 PM • Last activity: Mar 27, 2021, 05:58 PM

7 votes

1 answers

390 views

Should the option "--rcfile /dev/null" have the same effect as "--norc" when invoking bash?

bash arch-linux shopt

To avoid the XY problem scenario, I'll explain why I'm asking this question. I remember I had `shopt -s extglob` set in my `~/.bashrc` file, because things like `@(pattern-list)` do work. However, I've just looked into `~/.bashrc` and that option is not set. So I decided to see where it comes from,...

To avoid the XY problem scenario, I'll explain why I'm asking this question. I remember I had shopt -s extglob set in my ~/.bashrc file, because things like @(pattern-list) do work. However, I've just looked into ~/.bashrc and that option is not set. So I decided to see where it comes from, and discovered that - if I launch another shell via bash --norc and then run shopt I see the line extglob off, - whereas, if I launch it via bash --rcfile /dev/null, then shopt shows that extglob on, which doesn't really help me in find out which file is extglob is set in. Based on a comment, PS4=' $BASH_SOURCE:$LINENO: ' bash -lixc true |& grep extglob gives

/usr/share/bash-completion/bash_completion:45: shopt -s extglob progcomp
   /usr/share/bash-completion/bash_completion:45: shopt -s extglob progcomp

Enlico (2258 rep)

Mar 11, 2021, 08:18 AM • Last activity: Mar 11, 2021, 03:55 PM

-2 votes

2 answers

95 views

mv cdable_vars - where has my .bashrc gone?

bash mv shopt

I thought it would be clever to have an alias to my `dotfiles` repo, where I keep my dotfiles such as `.bashrc`. Following a [recommendation](https://stackoverflow.com/a/39839346/4556479), I added this to my `.bashrc`: ```bash shopt -s cdable_vars export dotfiles=$HOME/dotfiles/ ``` Then I wanted to...

I thought it would be clever to have an alias to my dotfiles repo, where I keep my dotfiles such as .bashrc. Following a [recommendation](https://stackoverflow.com/a/39839346/4556479) , I added this to my .bashrc:

shopt -s cdable_vars
export dotfiles=$HOME/dotfiles/

Then I wanted to test, by moving my bashrc to dotfiles with:

mv .bashrc dotfiles

However, the bashrc never appeared in $HOME/dotfiles/ - it's also not in my home folder anymore. Anyone knows where it could be gone?

Alex (137 rep)

Dec 13, 2020, 08:21 AM • Last activity: Dec 13, 2020, 10:48 AM

1 votes

0 answers

382 views

is it enough to set "shopt -s nocaseglob" once / script?

bash shopt

Is it enough to set `shopt -s nocaseglob` once in a bash-script, or do I need to set it before every function in the script. Do I need to turn it on again after the script is completed or is this only a temporary setting for just that terminal?

                                  Is it enough to set shopt -s nocaseglob once in a bash-script, or do I need to set it before every function in the script.

Do I need to turn it on again after the script is completed or is this only a temporary setting for just that terminal?

JoBe (417 rep)

Aug 10, 2020, 05:36 PM • Last activity: Aug 10, 2020, 07:18 PM

1 votes

1 answers

485 views

bash overrides the history even with histappend set to on

bash shopt

I'm trying to write the bash history to a file (`...| 1 |...`), then change one character (`...| 2 |...`) in `HISTTIMEFORMAT` environment variable run couple commands and being able to see commands from the first run as well as commands from the second run. Questions: 1. Why when I change the value...

I'm trying to write the bash history to a file (...| 1 |...), then change one character (...| 2 |...) in HISTTIMEFORMAT environment variable run couple commands and being able to see commands from the first run as well as commands from the second run. Questions: 1. Why when I change the value it changes all the values before that in the same "column"? 2. Why shopt -s histappend doesn't make a difference? OS:

[root@test ~]# cat /etc/*-release
CentOS release 6.10 (Final)

[root@test ~]# export HISTTIMEFORMAT='%a %h %d | %T | 1 |'; shopt -s histappend; echo 1; history 3
  872  Wed Jun 17 | 22:14:48 | 1 |export HISTTIMEFORMAT='%a %h %d | %T | 1 |'; shopt -s histappend; echo 1; history 3
  873  Wed Jun 17 | 22:14:50 | 1 |export HISTTIMEFORMAT='%a %h %d | %T | 1 |'; shopt -s histappend; echo 1; history 3
  874  Wed Jun 17 | 22:14:52 | 1 |export HISTTIMEFORMAT='%a %h %d | %T | 1 |'; shopt -s histappend; echo 1; history 3
[root@test ~]# export HISTTIMEFORMAT='%a %h %d | %T | 2 |'; shopt -s histappend; echo 2; history 3
  873  Wed Jun 17 | 22:14:50 | 2 |export HISTTIMEFORMAT='%a %h %d | %T | 1 |'; shopt -s histappend; echo 1; history 3
  874  Wed Jun 17 | 22:14:52 | 2 |export HISTTIMEFORMAT='%a %h %d | %T | 1 |'; shopt -s histappend; echo 1; history 3
  875  Wed Jun 17 | 22:15:02 | 2 |export HISTTIMEFORMAT='%a %h %d | %T | 2 |'; shopt -s histappend; echo 2; history 3

Vor (113 rep)

Jun 17, 2020, 11:17 PM • Last activity: Jun 18, 2020, 12:34 AM

2 votes

1 answers

1145 views

Aliases don't work in interactive zsh

zsh alias shopt

I have a curious problem where my aliases are listed when I type `alias`, but they are not executable. Here, I try to alias `d` to `date`: ``` % which alias alias: shell built-in command % alias d=/usr/bin/date ``` But it doesn't run: ``` % d zsh: command not found: d % /usr/bin/date Sun 19 Apr 2020...

I have a curious problem where my aliases are listed when I type alias, but they are not executable. Here, I try to alias d to date:

% which alias
alias: shell built-in command
% alias d=/usr/bin/date

But it doesn't run:

% d
zsh: command not found: d
% /usr/bin/date
Sun 19 Apr 2020 20:30:06 +07

Is there some obscure option that I'm missing?

Tom Hale (32892 rep)

Apr 19, 2020, 01:42 PM • Last activity: Apr 20, 2020, 06:07 PM

2 votes

1 answers

1887 views

Extended globbing inside script - what am I doing wrong?

bash scripting wildcards shopt

so I'm trying to select a range of files using an interactive script. The end goal is to use the `read` command but for demonstration here I assigned the `glob` variable manually #!/bin/bash shopt -s extglob # read -rp "Please enter a globbing string:"$'\n' glob # This will give me an error (See bel...

                                  so I'm trying to select a range of files using an interactive script.

The end goal is to use the read command but for demonstration here I assigned the glob variable manually

    #!/bin/bash
    shopt -s extglob
    # read -rp "Please enter a globbing string:"$'\n' glob
    
    # This will give me an error (See below)
    glob=*2020_04_03_{06..18}.jpg
    /bin/ls -la /mnt/drive1/images/*/*/${glob}

    # While this will return the desired files
    /bin/ls -la /mnt/drive1/images/*/*/*2020_04_03_{06..18}.jpg
    
The error is as follows:

    Error /bin/ls: cannot access "/mnt/drive1/images/*/*/*2020_04_03_{06..18}.jpg": No such file or directory

So what am I missing here in either assigning the glob variable or appending the glob variable to my path?

**Solution**:

I found a solution but I'm not quite sure why but

    bash <

Guidable (29 rep)

Apr 5, 2020, 07:00 PM • Last activity: Apr 9, 2020, 03:45 PM

1 votes

1 answers

136 views

Which bash shell options are used by the parser?

bash shopt

Restricting our focus exclusively to `bash`, in [this answer][1] on Stack Overflow it is reported the following. > `extglob` is a flag used *by the parser*. Functions, compound commands, &c. are parsed in entirety ahead of execution. Thus, `extglob` must be set before that content is parsed; setting...

                                  Restricting our focus exclusively to bash, in this answer  on Stack Overflow it is reported the following.

> extglob is a flag used *by the parser*. Functions, compound commands, &c. are parsed in entirety ahead of execution. Thus, extglob must be set before that content is parsed; setting it at execution time but after parse time does not have any effect for previously-parsed content.
>
> This is also why you can't run shopt -s extglob; ls !(*.txt) as a one-liner (when extglob is previously unset), but must have a newline between the two commands.

However, this is not true for other shell options. Consider e.g. the following.

    $ ls -a
    .  ..  .hiddenFile  file1  file2  file3
    $ shopt dotglob
    dotglob        	off
    $ echo *
    file1 file2 file3
    $ shopt -s dotglob; echo *
    .hiddenFile file1 file2 file3
    
**Is it documented somewhere which shell options are used by the parser like extglob and therefore cannot be enabled within a group command that uses them?**

In the shopt page in the bash manual  nothing about the behaviour above seems to be mentioned.

                                

Axel Krypton (336 rep)

Mar 18, 2020, 02:07 PM • Last activity: Mar 18, 2020, 03:05 PM

0 votes

1 answers

562 views

Does setting the bash shell option 'checkhash' actually improve the performance of bash commands?

bash shopt

__Premise:__ In the process of modifying `.bashrc`, and going through the [bash manual for shopt online](https://www.gnu.org/software/bash/manual/html_node/The-Shopt-Builtin.html) page for the different shell options that can be handled by `shopt`, I came across the option `checkhash`, which accordi...

__Premise:__ In the process of modifying .bashrc, and going through the [bash manual for shopt online](https://www.gnu.org/software/bash/manual/html_node/The-Shopt-Builtin.html) page for the different shell options that can be handled by shopt, I came across the option checkhash, which according to the description:

checkhash
    If this is set, Bash checks that a command found in the hash table exists 
    before trying to execute it. 
    If a hashed command no longer exists, a normal path search is performed.

__Questions:__
1. Is this option useful, i.e, does it increase the performance of the bash commands? 2. If, yes, why is the __default value__ set to off? 3. If, no, why does the option exist in the first place, is it something to do with older hardware?

RG7 (115 rep)

Feb 21, 2020, 06:11 AM • Last activity: Feb 21, 2020, 06:28 AM

Showing page 1 of 20 total questions