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(learning bash)
I was trying to check the bash version so I typed /bin/bash -v.
That outputted a whole lot of text to the screen (contents of .bashrc, and other files sourced from it).
Could I have screwed up something (like overwriting some config files/setting incorrect environment variables etc.) due to that command?
I also can't find documentation on what the -v switch is for.
The -v parameter for bash stands for verbose, and instructs bash to print out as much information as possible about what it is doing. On startup, it will print out all the configuration it is reading in.
To print out the version information for bash, use bash --version.
echo "$BASH_VERSION". There's also a special array (BASH_VERSINFO) containing each version number in separate elements. if ((BASH_VERSINFO[0] < 4)); then echo "Sorry, you need at least bash-4.0 to run this script." >&2; exit 1; fi
[ "${BASH_VERSINFO}" -lt 4 ] or [ "${BASH_VERSINFO[0]}" -lt 4 ]
which bash (located at /bin/bash on most systems), which may be different than the version that happens to be running in some prompt or script. (For example, a script started with #!/usr/local/bin/bash might use a different version). Other methods (documented in other answers) may also be helpful.
When running bash (e.g. from gnome-terminal) you can check value of BASH_VERSION environment variable.
$ echo $BASH_VERSION
4.2.37(1)-release
If the value is empty, you are not running bash.
bash --version, because it confirms that you are currently running bash, not just that you have bash installed on your system.
BASH_VERSION does not ensure that you are running bash: export BASH_VERSION; csh -c 'echo $BASH_VERSION $SHELL $shell', so $BASH_VERSION may be set in csh as well
$SHELL --version, but again SHELL might be overwritten (and all shell do not support the --version flag).
$BASH_VERSION is very strongly advised over $SHELL --version. Needing this on a Mac trying to make sure I'm not using the system's bash over a package managed (up to date) bash has $SHELL=/bin/bash, but is correctly configured and running my desired version. Can't give another upvote here, unfortunately.
Jan 9, 2020 at 4:00
There's a key shortcut that instructs current shell information to show up:
Ctrl+x Ctrl+v
From man bash
display-shell-version (C-x C-v)
Display version information about the current instance of bash.
This is the best choice if you have messed with environment variables.
No, everything is alright. From man bash:
--verbose
Equivalent to -v.
It is just not as silent as usual. Try
--version
instead.
The usual --version may give you too much multi-line boilerplate so what I am using is
bash -c 'echo $BASH_VERSION'
bash shell. One way this is useful is that it doesn't need the shell currently being used to be bash. Another is that, even in bash, it's possible (though not good) to set BASH_VERSION to a different value. It can even be exported as an environment variable. Yet even after running export BASH_VERSION=foobar, the method given here works, since the new bash shell resets its own BASH_VERSION automatically before performing the parameter expansion that reads it.
Sep 28, 2017 at 17:02
bash --version says 4.3.48(1)-release and apt-cache policy bashsays 4.3-14ubuntu1.2 and I have checked that the executable bash file comes from the package 'bash'. How should this be interpreted? There is a similar mismatch for usb-creator-gtk, and in that case the apt-cache output is correct. -- Can we conclude that the higher version number is the correct one (and someone forgot to update the other one)?
4.3.48... is the version of Bash, 4.3-14... is the version of the bash package.
To only get the version and not the multiline text:
$ bash --version | head -1 | cut -d ' ' -f 4
bash --version | awk 'BEGIN{ RS="[ \n]"; FS="[ \n]" }s{ print $0; exit}/version/{ s=1 }'
bash -vyou invoked a new bash shell with verbose mode activated, so you will see verbose output for further commands (at the very minimum you'll seeprintf "\033]0;%s@%s:%s\007" "${USER}" "${HOSTNAME%%.*}" "${PWD/#$HOME/~}"). To end the verbosity, typeexitcommand - you will be back in the original non-verbose bash shell (or whatever shell you were in).