I am able to get expected output using:
puts `ls` # listing of current directory
But I am unable to get the command history using the similar call:
puts `history` # Error - No such file or directory - history (Errno::ENOENT)
history command is disabled in non-interactive sessions, but you should be able to access history directly form the file:
`cat ${HOME}/.bash_history`
(tested on Ubuntu)
history is not a built-in command in the shell. In zsh, for instance, it’s an alias to this:
fc -l 1
You can use that command from Ruby to get the history. But I don’t think it’ll work how you expect, since the shell that Ruby starts up will have no history!
ls is an "external" command that is usually located in /bin/ls. history on the other hand is not an external command but is built-in into your shell, usually bash or zsh.
Now in the shellouts, Ruby uses the /bin/sh shell by default which does not have history commands available.
Note that even though /bin/sh and /bin/bash are usually the same binary, Bash behaves differently when executed as /bin/bash. That's what you are seeing here.
Related
I use vim's :! external command function all the time, usually providing % as an argument to the shell command. For example :
:!psql -f %
I also have a lot of bash shell functions in my .bashrc that I use. For example:
psql-h1 ()
{
/usr/bin/psql -hh1 -d mydb "$#"
}
These bash functions aren't available from :! inside of vim. Is there a way to make them available?
Export your functions. That is:
psql-h1() { /usr/bin/psql -hh1 -d mydb "$#"; }
export -f psql-h1 ### <-- THIS RIGHT HERE
This will make them available to any copy of bash run as a child process, even if it's a noninteractive shell and so doesn't read .bashrc.
An alternative to exporting your functions (which may no reach Vim is there's a non-Bash shell in between; see here for such a case), you can instruct Vim to start an interactive shell, so that your .bashrc is read. Just pass the -i flag to Bash, via Vim's :help 'shellcmdflag'.
:set shcf=-ic
This answer assumes your vim isn't actually using bash to invoke the remote commands - this can be tested by running :!echo $0 in vim.
Specifically for vim, add:
set shell=/bin/bash
to your .vimrc.
In general, there's two strategies I've found to sometimes work when trying to get other programs to invoke my preferred shell:
export SHELL=/bin/bash
in eg. the .profile file, or:
ln -fsn /bin/bash /bin/sh
which updates the sh symlink to point to bash instead.
On many systems (certainly Ubuntu), /bin/sh is a symlink to a sh-compatible shell (such as bash), rather than the sh shell itself. Given this fact, some programs (I've seen this behaviour in GHC) seem to invoke /bin/sh, so changing where it points to will cause the programs to use bash instead.
The accepted answer didn't work for me. I'm going to go with setting shcf, as suggested elsewhere:
:set shcf=-ic
but another solutions is
!source ~/.bashrc && psql ...
Unfortunately, no solution allows the auto-completion for the command I'm creating to work properly. (The auto_completions suggested are for names of files in my current directory, rather than the ones I specified as follows in .bashrc
complete -F _generate_foo_completions foo
I am not a Solaris expert and I am trying to create a shell script that will change my prompt to PWD and the ksh to bash and I have this:
PS1='$PWD $ ' exec bash --noprofile --rcfile /dev/null
or
PS1='\w $' exec bash --noprofile --rcfile /dev/null
Both of them dont work from a sh. if i add them from the command line then the first time my bash appears on prompt and the second time the PS1='$PWD $' kicks in and my prompt changes.
Firstly, why is PS1='$PWD $' not working from shell script . and why do i have to run the command from command line twice to acheive my results.
Also, in my export/home/syed/ directory there are three files local.login, local.profile, and local.cshrc. is there any way i can use them that when ever i log in i dont need to run my shell script and upon login i get bash shell and my prompt as i want it
(am i asking too much, i dont like the ksh as it does not have any features like up arrow recall last commands and tab auto complete features)
thanks
Syed...
When you exec from within a script, the script is what is replaced, not the parent shell.
Try sourcing the script rather than running it.
Also, in Solaris, you can use passwd -e to change your login shell.
You may be able to symlink ~/.profile to your existing ~/local.profile (or similar). Note that .cshrc is for the C Shell and is not compatible with ksh or Bash.
If you want that your default shell will be bash, change it in /etc/passwd
When you exec bash it sets up its own environment from scratch. Pass it an --rcfile containing the settings you would like for it to inherit.
How can I tell what type my shell is? ie, whether it's traditional sh, bash, ksh, csh, zsh etc.
Note that checking $SHELL or $0 won't work because $SHELL isn't set by all shells, so if you start in one shell and then start a different one you may still have the old $SHELL.
$0 only tells you where the shell binary is, but doesn't tell you whether /bin/sh is a real Bourne shell or bash.
I presume that the answer will be "try some features and see what breaks", so if anyone can point me at a script that does that, that'd be great.
This is what I use in my .profile:
# .profile is sourced at login by sh and ksh. The zsh sources .zshrc and
# bash sources .bashrc. To get the same behaviour from zsh and bash as well
# I suggest "cd; ln -s .profile .zshrc; ln -s .profile .bashrc".
# Determine what (Bourne compatible) shell we are running under. Put the result
# in $PROFILE_SHELL (not $SHELL) so further code can depend on the shell type.
if test -n "$ZSH_VERSION"; then
PROFILE_SHELL=zsh
elif test -n "$BASH_VERSION"; then
PROFILE_SHELL=bash
elif test -n "$KSH_VERSION"; then
PROFILE_SHELL=ksh
elif test -n "$FCEDIT"; then
PROFILE_SHELL=ksh
elif test -n "$PS3"; then
PROFILE_SHELL=unknown
else
PROFILE_SHELL=sh
fi
It does not make fine distinctions between ksh88, ksh95, pdksh or mksh etc., but in more than ten years it has proven to work for me as designed on all the systems I were at home on (BSD, SunOS, Solaris, Linux, Unicos, HP-UX, AIX, IRIX, MicroStation, Cygwin.)
I don't see the need to check for csh in .profile, as csh sources other files at startup.
Any script you write does not need to check for csh vs Bourne-heritage because you explicitly name the interpreter in the shebang line.
Try to locate the shell path using the current shell PID:
ps -p $$
It should work at least with sh, bash and ksh.
If the reason you're asking is to try to write portable shell code, then spotting the shell type, and switching based on it, is an unreliable strategy. There's just too much variation possible.
Depending on what you're doing here, you might want to look at the relevant part of the autoconf documentation. That includes an interesting (and in some respects quite dismal) zoology of different shell aberrations.
For the goal of portable code, this section should be very helpful. If you do need to spot shell variants, then there might be some code buried in autoconf (or at least in one of the ./configure scripts it generates) which will help with the sniffing.
You can use something like this:
shell=`cat /proc/$$/cmdline`
Oh, I had this problem. :D
There is a quick hack, use ps -p $$ command to list the process with PID of the current running process -- which is your SHELL. This returns a string table structure, if you want, you can AWK, or SED the shell out...
The system shell is the thing you see when you open up a fresh terminal window which is not set to something other than bash (assuming this is your default SHELL).
echo $SHELL
Generally, you can find out all the constants defined by running
set
If the output is a lot of stuff then run
set | less
so you can scroll it from the top of the command line or
set > set.txt
To save the output to a file.
Invoking a different interactive shell to bash in your terminal does not mean that your system shell gets changed to something else i.e. your system shell is set to bash although you invoke a csh shell from a bash shell just that one session.
The above means that typing /bin/csh or /bin/python in bash or whatever does not set the system shell to the shell you invoked, at all.
If you really want to see the SHELL constant change then you need to set it to something else. If successful you should see the new shell whenever you open a fresh terminal...
It's old thread but...
In GNU environment You can sh --help and get something like
BusyBox v1.23.2 (2015-04-24 15:46:01 GMT) multi-call binary.
Usage: sh [-/+OPTIONS] [-/+o OPT]... [-c 'SCRIPT' [ARG0 [ARGS]] / FILE [ARGS]]
Unix shell interpreter
So, the first line is shell type =)
I just started using a Solaris 10 (Sparc) box where I telnet in and get confronted with a very unfriendly interface (compared to the standard bash shell I use in cygwin or linux) --- the arrow keys do not work as I expect them to. Being an NIS system, changing the shell is not as easy as using the "chsh" command. And setting the SHELL environment variable in ~/.login and ~/.profile is not working for me. So I'm thinking that I may need to write a script to determine if bash is running the script and starting bash if the answer is no. My first attempt, trying to invoke /bin/bash from ~/.profile seems to work but kind of doesn't feel right. Other suggestions? And how do I tell programmatically which shell is actually executing?
You can tell what shell is running with echo $0. For example:
$ echo $0
-bash
If you're changing shell you probably want to replace the current shell process rather than be a child of it, so use exec.
Also, you want to pass bash the -l flag so it acts as if it has been called as part of the login process.
So you'll want something like:
exec bash -l
You are probably running with ksh(1) on Solaris. You have several options, read the manpage for ksh and configure it or install another shell you're more familiar with like bash. I'd personnaly recommend zsh.
I am new to programming and am trying to follow an example which uses #! comment in ruby.
I am consistently get the message:
bash: matz.rb: command not found
I am using this comment:
#! /usr/bin/env ruby
I have tried it with and without the space after ! as well as with and without the env.
when I use the
$ which ruby
ruby is in: /usr/bin/ruby
I have also gone into the operating system and changed the permissions on the file matz.rb to rwx for all users w/ no effect. Am I doing something wrong or do I have my system set up incorrectly?
The /usr/bin/env part is fine. You need to give bash the path to matz.rb when you run it. If you're in the directory with matz.rb, type "./matz.rb". The directory "." means the current directory - bash doesn't look there by default when running programs (like Windows does).
The env program (/usr/bin/env) searches the executable search path - the PATH environment variable - for the ruby program as if you typed it at the command prompt, and runs that program. The shebang comment doesn't do this. If you want to give your script to other people who might not have ruby installed in the same place as you, then you should use the "#!/usr/bin/env ruby" comment so that it will work as long as they can run ruby by typing "ruby".
If you're in the same directory as the matz.rb file, be sure to run it as
$ ./matz.rb
and not just
$ matz.rb
Here's a shell session demonstrating this working:
$ ls -la m*
-rwxr-xr-x 1 gareth gareth 32 8 Jan 08:46 matz.rb
$ cat matz.rb
#!/usr/bin/env ruby
puts "Matz"
$ matz.rb
-bash: matz.rb: command not found
$ ./matz.rb
Matz
Your file wasn't created on Windows was it? If it has \r\n line endings, that will upset bash. You can open it with Vim and check:
vi matz.rb
:set ff=unix
:wq
If when you tab-complete the "ff=" part it says dos, then it has the wrong file format. Alternatively, run dos2unix and try to run the file again:
apt-get install sysutils
dos2unix matz.rb
It sounds like you're on a Unix/Linux system and just typing matz.rb on the command line. If you're trying to execute a command in the current directory, you need to call it like ./matz.rb. The "./" tells it to look in the current directory rather than just /usr/bin and friends.
I failed to see any answer indicating you to change the executable mode of the file, so you might wanna try and do
chmod +x matz.rb
before you go and try doing
./matz.rb
Also it might be better not to attach a .rb extension to the file, such is the case for normal ruby / rails scripts e.g. script/generate, script/console etc.
You can use the 'shebang' line with either:
#!/usr/bin/ruby
#!/usr/bin/env ruby
But the script needs to be executable (you indicated it is) and in your shell $PATH.
echo $PATH
Put the script in one of those directories, or modify your path, otherwise specify the full path to it, for example:
export PATH=$PATH:/home/user/bin
or one of these:
./matz.rb
/home/user/bin/matz.rb
You can also run the Ruby interpreter passing the script filename as an argument, and it will be executed. This is particularly useful if you have another version of Ruby installed on your system (say, for testing, like Ruby Enterprise Edition, REE):
/usr/bin/ruby matz.rb
/opt/ree/bin/ruby matz.rb
Have you tried the ShaBang as following to directly point to ruby?
#! /usr/bin/ruby
Then you call the script from the commandline as
./matz.rb
Under Unix/Linux systems the dot in front of a command to search for the command in the current directory. If you give a path like /usr/bin/ruby, it will search in the current directory for a directory called usr...
A command without a dot/ in front is searched in locations specified by the path variable of the environment.
A command with a / on the beginning is searched exactly from root following the specified path.
Inside your ShaBang, you want to specify the exact path to the interpreter so "/usr/bin/ruby" is the correct one. On the commandline, where you want your script to be executed, you need to call the script with "./matz.rb" otherwise the bash will search a command like /usr/bin/matz.rb what leads to your errormessage.