I am trying to launch a legacy application in GDB, and it requires that it's argv[0] value not contain anything other than alphanumeric characters.
Whenever I launch the program in GDB it seems that it expands the name to be the full path before running the program, so I get an error like (because it can't deal with the slashes):
"Cannot find /home/user/myapp ..."
Is it possible to run a program in GDB with a relative path, so that it will just see "myapp"?
Gdb normally runs target commands using the shell command line
exec program_pathname program_arguments
But it has a set exec-wrapper command that will change this to
exec exec_wrapper program_pathname program_arguments
The exec_wrapper is often another command, but it can be an option that the exec command accepts.
Many shells (bash, zsh, ksh93) support a -a option to the exec command to set argv[0].
So, if your shell supports exec -a, you can do the following to invoke /home/user/myapp with argv[0]==myapp:
(gdb) set exec-wrapper -a myapp
Related
I try to use julia-1.6 with VScode, but I cannot find a path to the executable.
When I try to change the working directory via the julia prompt to the executable, I get an error message saying it's not a directory:
julia> cd("/Users/jjdegruijter/bin/julia")
Can anybody tell how to do it properly?
To get the path to your Julia executable, from the REPL, do:
joinpath(Sys.BINDIR, "julia")
You can start a REPL by just running julia from the terminal, or by pressing Alt-J Alt-O in VS Code (you can also instead type Ctrl-Shift-P, then choose Julia: Start REPL from that list).
Or, you can also directly run the above command from the terminal without starting a REPL: julia -e 'println(joinpath(Sys.BINDIR, "julia"))'.
If you just want to change working directory to the directory containing the executable (though I'm not sure why you'd want that here):
cd(Sys.BINDIR)
I tried running bundle exec create_namespace command on Ubuntu. It gives error but the exitcode = 0. Is there an alternative way to capture the failure of the bundle exec create_namespace command?
bundle exec executes a command in the context of the bundle (from bundle exec --help ).
If you pass a executable name that is not found, e.g. bundle exec thisisnotwhatyouarelookingfor, it will exit with a status code != 0.
"Your" command (create_namespace) must be a self-provided script, most likely something you are working on, or something located in the repository you play around with. It is then the responsability of that script to exit with the "correct" exit code.
You'd need to provide more information about your environment and that executable for people to dive into the issue. To find the executable yourself, a find . -name "create_namespace*" should point you in the right direction (most likely in ./binor./exe` if it is a gem and follows conventions).
TL;DR Most likely bundle exec does not fail (it starts the create_namespace "command" in the correct environment), but the command itself fails without setting the exit code properly.
When I try to run a shell command in ipython or the julia repl it just says
shell> ls
zsh:1: command not found: ls
Not sure if it matters, but I have my path set in zshenv instead of zshrc so that emacs shell works.
Any ideas?
Edit:
I'm on macOS 10.14.6
For Julia, The shell> REPL prompt does in fact use a shell to execute its commands (on non-Windows systems). It effectively does something like run(`$shell -c ls`), and for most shells (including zsh) this means "non-interactive" mode and limits the number of init files that get loaded. You want to make sure your shell is working in this mode; I'd guess that if you type zsh -c ls at your terminal it'll be similarly broken.
Alternatively, you can customize which shell Julia uses through an environment variable. Setting JULIA_SHELL=/bin/sh is probably a safe bet — Julia uses that environment variable if it is set, otherwise it uses SHELL, and finally it falls back to /bin/sh if neither is set.
I'm not as familiar with ipython, but I'd wager it's doing something similar.
Can I invoke "rake jobs:work" automatically after running "rails s" in console?
Currently, after running rails s in cmd I will also run rake jobs:work in the other console, what i want to happen is After running "rails s" the jobs:work will automatically start.
The right way to go about this would be to use a process manager, like Invoker or Foreman. There is ample documentation on the links, but it boils down to the following steps:
Install the software
Create a configuration file where you declare what processes do you intend to run. Both support Procfile style declaration.
Use the command line client to start the process manager.
Based on my personal experience, I highly recommend Invoker, it goes beyond just a process manager, and packs in a few more handy features, like support for .dev local domain.
One you can do is simply:
rails server & rake jobs:work
It'll run rails server as background job, which you can get back to foreground with fg. It can be annoying that you'll get output from both processes mixed.
I'm not sure what are your needs and what you expect but maybe it would be good for you to use screen (or tmux) to run them in parallel and be able to switch between.
You can do your own .screenrc script which will run the server and any other commands when automatically for you.
There is a little problem that if you run the server from it and you close it (ctrl+c) than you'll loose it's screen window. Fortunately there is a solution for that as well (worked-out on the SO as well - you can read more about it here)
So, I use some helper script for that .run_screen (don't forget to chmod +x it):
#!/bin/bash
/bin/bash -i <<<"$*; exec </dev/tty"
Than I have .screenrc_rails file:
#shell -${SHELL}
caption always "%n(%t) %= %{b}#%H[%l] : %{r}%c:%s"
termcapinfo xterm ti#:te#
termcap xterm 'AF=\E[3%dm:AB=\E[4%dm'
terminfo xterm 'AF=\E[3%p1%dm:AB=\E[4%p1%dm'
startup_message off
screen -t server 2 ${HOME}/.run_screen rails s
screen -t spork 3 ${HOME}/.run_screen bundle exec spork
screen -t dev_log 4 ${HOME}/.run_screen tail -f ./log/development.log
screen -t test_log 5 ${HOME}/.run_screen tail -f ./log/test.log
screen -t bash 0
screen -t bash 1
And an alias ( screenr(ails) ) defined at .bash_profile:
alias screenr='screen -c ~/.screenrc_rails'
If you don't know screen than start from ctrl+a, ". ctrl+a, ? will give you some help.
I hope you'll enjoy it.
whenever I switch directory in my terminal, I have to run the command "/bin/bash --login" before I can run rails/rake related commands. If I don't, I get an error saying "the program "rails" can be found in the following packages: ..."
Any advice?
By default some servers do not allow this due to permissions reason. You can place this in
~/.bashrc and it will automatically work when you open a new terminal
As per bash man page.
When an interactive shell that is not a login shell is started, bash
reads and executes commands from ~/.bashrc, if that file exists. This
may be inhibited by using the --norc option. The --rcfile file option
will force bash to read and execute commands from file instead of
~/.bashrc.
When bash is started non-interactively, to run a shell script, for
example, it looks for the variable BASH_ENV in the environment,
expands its value if it appears there, and uses the expanded value as
the name of a file to read and execute. Bash behaves as if the
following command were executed:
if [ -n "$BASH_ENV" ]; then . "$BASH_ENV"; fi but the value of the
PATH variable is not used to search for the file name.
The file is just shell commands. It is typically used to change prompts, set environment variables, and define shell procedures. Traditionally, the file .profile is used for this purpose, but bash has so many extensions that it needs its own startup file for users that want to put bashisms in startup files.
Easy solution:
Just open terminal. GO to Edit menu from terminal navigation bar, Select "Profile Preferences", It will open "edit profile pop-up". Select "Title and Command" button and "check Run Command as login shell"
ctrl + alt + t -> Edit -> Profile Preferences -> Title and Command -> Check Run command as login shell
Close the terminal and open again. Next time you don't need to "/bin/bash --login"