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BASH Debugging

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Bashdb is nice debugger for bash, but usually it is not installed by default. You either need to install it from source using version 3 if you have bash 3 and version 4 if you have bash 4.1 or bash 4.2. 

RHEL 7 uses bash 4.2, so for it you can use bashdb-4.4-1.0.1.tar.gz from bash debugger download -

The versions are stored at the tree at

See BASH with Debugger and Improved Debug Support and Error Handling or to the link to the tarball.

Command are similar to Perl debugger so users of Perl can instantly feel at home using it. 

Documentation is available at



 Installation consist of just three commands

1. Make your current directory the debugger directory.

2. run commands

cd bashdb*           # <-- put name of release for Bash 4.2 or other version that you have..
./configure          # use --with-bash-src to speed up bash debugging
make && make check 
su -c 'make install' # should run as root

If those steps run OK, you should have debugger available in /usr/local/bin   and you can call it using the command

bashdb --help
[root@icontainer home]# bashdb --help
   bashdb [OPTIONS] <script_file>

Runs bash <script_file> under a debugger.

    -h | --help             Print this help.
    -q | --quiet            Do not print introductory and quiet messages.
    -A | --annotate  LEVEL  Set the annotation level.
    -B | --basename         Show basename only on source file listings.
                            (Needed in regression tests)
    --highlight | --no-highlight
                            Use or don't use ANSI terminal sequences for syntax
    --init-file FILE        Source script file FILE. Similar to bash's
                            corresponding option. This option can be given
                            several times with different files.
    -L | --library DIRECTORY
                            Set the directory location of library helper file: /usr/local/share/bashdb/
    -c | --command STRING   Run STRING instead of a script file
    -n | --nx | --no-init   Don't run initialization files.
    --tty | --terminal DEV  Set to terminal in debugger output
    -T | --tempdir DIRECTORY
                            Use DIRECTORY to store temporary files
    -V | --version          Print the debugger version number.
    -X | --trace            Set line tracing similar to set -x
    -x | --eval-command CMDFILE
                            Execute debugger commands from CMDFILE.


You can use debugger even without installation. In this case you need to be in the directory you untared it and use the option “-L .”:

bash -L ./bashdb script-to-be-debugged options-to-debugged-program

If bashdb has been installed you don’t need to use option “-L .” Instead you would type simply

bashdb script-to-be-debugged options-to-debugged-program

I would recommend to check syntax of the bash script before using the debugger using option "-n", for example 

bash -n

Let's summarize the essentials of the debugger invocation:

  1. type bash --debugger script-name  or bashdb script-name to start the BASH debugger. 
  2. type bashdb -c command string to run a command or one-liner under the debugger.
  3. Or type bashdb -h  to get help about options available (bashdb --help   works too)

Two useful commands are n (next) - next step and p (print) -- print the variable or expression. Type quit or C-d inside the debugger to exit. Other way to terminate the debugger is to use the kill command. kill -9 can be used in cases where quit doesn't work.

Getting help

Once inside the BASH debugger, you can always ask it for information on its commands, using the command help. You can use help (abbreviated h) with no arguments to display a short list of named classes of commands: >
bashdb<0> help
Available commands:
  /          debug    enable   help     next     show    step-      untrace
  alias      delete   eval     history  print    signal  tbreak     up     
  break      disable  examine  info     pwd      skip    trace      watch  
  commands   display  file     kill     quit     source  tty        where  
  condition  down     frame    list     restart  step    unalias  
  continue   edit     handle   load     set      step+   undisplay

Basdb documentation has several examples on how to use bashdb. See  Summary of the BASH Debugger

Dynamic activation from scripts

You can activate the debugger within the script. you can make an explicit call to the debugger in your script


Here is an example:

  for ((i=1; i<=10; i++)) ; 
        (( 5 == i )) && { _Dbg_debugger }
        echo "$date"
        sleep 2

You can also turn on and off line tracing with _Dbg_linetrace_on


There are also two front-ends available as well. One can also enter the debugger inside emacs via the command M-x bashdb after loading Emacs' Grand Unified Debugger, gud. See Using the BASH debugger from GNU Emacs.

And there is support in a DDD for bash.

Getting the bashdb

bashdb is available as a source package in Debian, Fedora and OpenSuse. The Ubuntu repository contains a package for bashdb too.

Please note that for bash 4.x you need   version of bashdb, version 4.x, while for bash 3.x. version of bashdb should be 3.0.x.

Tarball with debugger is downloadable from Sourceforge:

SUPPLEMENT: installation instruction in file INSTALL that comes with the tarball


0. download the latest bash debugger from:

The name should start out bashdb-3.x...

and ungzip/untar it. If you are reading this, you've probably done that already.

1. Make your current directory the debugger directory. If you want the bash extension command readarray that speeds up loading of large scripts than read step 3 of the long instructions especially down at the bottom. Basically to speed up the initialy debugger loading, you need the bash source headers and need to run configure using --with-bash-src.

configure, build, test, and install the debugger:

       cd bashdb-3.x... # <-- put name of release for 3.x...
       ./configure      # use --with-bash-src to speed up bash debugging
       make && make check 
       su -c 'make install'
On systems which don't install GNU Make by default you may have to use "gmake" instead of "make".

In creating files and directories for the bashdb, beware that the umask of the account performing the installation is consulted as it would be for any new file or directory. In particular, if your umask is, for example, 007, then directories that get created will have permission drwx------ which only allows that user to access the debugger support files. Since the root account sometimes has that umask, you may want to set the umask to something more permissive like 022, before running the "make install".

That's it!


This debugger needs a debugger-enabled version of Bash 3.2 or greater.

It is possible to try out the debugger without installing it by using the bashdb script that is in this directory. To do so you would invoke your script as follows, assuming you are currently in the directory (debugger) that you originally found this file in.

$BASH -L . ./bashdb *script-to-be-debugged* *options-to-debugged-program*

where $BASH above is bash 3.0 with debugging enabled.

A downside to this approach is that $0 in will be ``bashdb'' (or more likely ``./bashdb'') rather than the name of the script to be debugged. Also, the parameters to the bashdb invocation do not appear in a stack trace. If this is a problem, then you will have to install the debugger, or modify the script to be debugged to point to the debugger-enabled version of bash. For example if your script were in this directory (debugger) as well is your current working directory (as shown by ``pwd''), then having this at the beginning of your script:

#!/some-location/bash --debugger 
might also work.

For information on the differences between "bash --debugger" and bashdb, see Chapter 2 (Getting In and Out) of the bashdb documentation (, bashdb.html, or bashdb.texi)

Steps 0 and 1 you've probably already done if you are reading these instructions.

0. download the latest bash debugger from:

The name should start out bashdb-3.x...

1. ungzip/untar the bashdb debugger package.

      gzcat bashdb-3.x... | tar -xvpf -  # <-- put name of release for 3.x...

(There's a shorter way to do this GNU tar 1.15 or later)

2. Make your current directory the debugger directory.

   cd bashdb-3.x... 
3. Look at configure help options and decide what you want:
     ./configure --help

is your friend here.

On those OS's that support it, you will probably want the extension which enables reading large arrays fast and makes loading of large scripts (e.g. configure) much quicker. For this you need the bash source or at least the headers since we need to compile against that. And you need to tell configure where to use it via --with-bash-src.

It is important that the source match the bash that is going to be used when debugger. For example using bash release 3.1 source for an installed bash 3.0 binary will not work as there are incompatiblities. Should you have several bash binaries around, you can tell configure which one you want to use for the debugger via the option --with-bash.

For --with-bash use absolute paths, not relative paths or the regression tests will fail.

4. configure the debugger to suit your needs:

     ./configure  # you may want to add options gleened from step 3 above.
                  # in particular --with-bash-src.

There is a lot of verbiage, but do pay attention to any errors or warning you see here.

5. Build:

     make         # make options, but I think none are generally needed

Any old "make" should work, but if it doesn't, use GNU make (sometimes installed as "gmake". Again, even though there is verbiage pay attention to errors. If you don't have texi2html you may see some errors in building HTML pages; these you can ignore.

6. Run the regression tests:

    make check   # or gmake check
7. Install the debugger:
     su -c 'make install'

As above, pay attention to errors. In particular here if you don't have permission to fully install or overwrite existing files you may get a message that you can't run "bash --debugger" but must use the "bashdb" script. See above for a larger discussion of the difference.

No, really. that's it!


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