Hi I am having a problem with setting alias in mac after I start the screen command, I have alias for working with git, like
commit=git commit
they work as I expect when I start my terminal (iTerm2), but then sometimes I use screen to have simultaneous instances in remotes servers and virtual machines I work with. After this the alias disappear(command not found).
Does anyone know why or how solve it?
To make the alias work, you must use the alias command. For example, to create an alias in Bash you do:
$ alias commit="git commit"
This works temporarily ie.: in your current shell. In order to make it "stick", you must put it in your ~/.bashrc. That will make it be sourced to all instances of Bash you'll invoke during your terminal session.
When you start screen, it starts a separate Bash too, so you'll be covered.
You write something about VMs. If you need this alias to work there, you must make ~/.bashrc on these VMs to have the same aliases. But that's the other story. You should already know how to achieve what you want.
You need to make sure your aliases are defined in ~/.bashrc to ensure they get included in all logins. You can test this out: edit your ~/.bashrc to include this line:
echo "bashrc"
And then edit your ~/.bash_profile to include this line:
echo "bash_profile"
You'll see when you start screen that only "bashrc" is displayed.
See this question for much more detail on the subject.
Related
I am having some issue in writing a simple executable .sh file via bash.
The order of operation as soon as I open a terminal (ctrl+alt+T) are:
pc:~$ roscd
pc:~/catkin_docking_ws/devel$ cd ..
pc:~/catkin_docking_ws$ cd devel/lib/tuginterface/
pc:~/catkin_docking_ws/devel/lib/tuginterface$ ./tuginterface
I have been investigating this small issue and came across this source which advises to change and rename the project as an alias and that is exactly what I tried to do:
alias proj="roscd"
alias proj2="cd .."
alias proj3="cd devel/lib/tuginterface/"
alias exec="./tuginterface"
My current executable file after many trials is:
#!/bin/bash
alias proj="roscd"
alias proj2="cd .."
alias proj3="cd devel/lib/tuginterface/"
alias exec="./tuginterface"
But it still does not work.
The same post advises to create a script and after that an alias in the startup file.
Please advise on how to solve this problem and sorry if it is a simple question but I don't seem to catch the mistake I am making.
The script doesn't need to define aliases. Aliases are commands that you can type yourself. The script can just execute the commands directly.
#!/bin/bash
cd ~/catkin_docking_ws/devel/lib/tuginterface
./tuginterface
I've combined the three cd commands into one that jumps straight to the correct directory.
"But I thought cd doesn't work in shell scripts?"
It depends what you're looking for. When a script changes directory it affects later commands in the script, so in that respect it does work. The change of directory is only inside the script, though. The person calling the script won't see the directory change. Their current directory is unaffected.
I have several bash aliases set in my .bashrc but they generate errors every time I open a new terminal. Each time a new terminal opens, two bash: cd: too many arguments will appear. The aliases work as intended, but I would like to solve the errors anyway. Here are the aliases in question:
alias .1="cd .."
alias .2="cd ../.."
alias .3="cd ../../.."
alias .4="cd ../../../.."
alias .5="cd ../../../../.."
alias .=".1" #Trouble maker
alias ..=".2"
alias ...=".3"
alias ....=".4"
alias .....=".5"
I have narrowed it down to alias .=".1" as the culprit creating the errors. I understand the . is its own command and I am slapping an alias on top of it. I am not sure this is the issue or not, but I have noticed when I remove this line the errors disappear. Furthermore, running the alias on the CLI itself does not generate the same errors... only when in the .bashrc does it generate the errors.
Things I have tried:
Quotations on both sides of =
Changing alias .=".1" to alias .="cd .."
Adding a space before alias command in an attempt to suppress output
Aliasing . means you are changing how subsequent shell commands include other shell scripts. Since . and source do the same thing in bash you might be able to fix this by making sure that they're only using source. Look in .bash_profile for instance. Bash looks at a variety of files while it is starting and .bashrc is probably getting read by .bash_profile and something in there is trying to . some other file.
But really, why? Can you just add a dot to each of these and be ok with it? The .. directory is one level up so that could make it easier to remember. Changing things like this that are fundamental to how the shell operates and glues together multiple scripts is going to keep tripping you up.
The alias that is causing the error is: alias .=".1". The single period is a synonym for the source command, which reads in and executes commands from the file you pass as its argument.
What you're essentially doing (unintentionally), is trying to change the behavior of the source command using an alias.
This question is an offshoot of my question on whether there's anything wrong with having aliases on a production server.
So I tried creating a shell script with some aliases
#!/bin/sh
echo "creating aliases..."
alias f='clear;cd ..;ls;pwd'
alias ff='clear;cd ../..;ls;pwd'
Did a chmod +x al.sh, and ran the script ./al.sh, but although the "creating aliases..." statement got printed, none of the aliases worked, because they were obviously active only until the script ran.
So is there a way I can run a script containing the aliases I want, which will remain active as long as the terminal session is active? The basic idea being, not to cause problems for colleagues who use the same server.
For cases when you want to store functions and aliases just for your session, I find it quite useful to have a file with them and sourcing it when I login the server.
So just place it somewhere like:
~/nav_alias_file.sh
And then just after sshing the server type:
source ~/nav_alias_file.sh
Note by the way that, as Sundeep expressed in comments, you do not need the shebang in that file.
If you use an alias in a terminal, e.g. alias a=b it will stay in the current terminal, but if you open another terminal you have to set up the alias again. In order to make the alias permanent you can add the alias to the .bash_profile and this will apply it to all the terminals permanently.
My question is how to set up an alias for all the terminals but only for the current session, i.e. if I log out the alias is gone.
Thanks
The general concept is to create a file like .session_aliases which contain your session aliases, then put a line like (notice the spaces around the [, ], and the . before .session_aliases—these are required):
[ -f .session_aliases ] && . .session_aliases
in your .bashrc (or .profile or .bash_profile or whatever). Then you just need to set up a script, run at session logout, which removes .session_aliases.
However, a quick search for "xlogout" suggests that there doesn't seem to be a universal script that gets called when you log out of your session. So the answer is going to be display-manager-specific.
You didn't mention which display manager you use, so I'm going to assume lightdm (given that that's the standard display manager for Ubuntu and Ubuntu is the most common distribution). You can follow the instructions here to set up a logout script when you end your lightdm session.
If you use a different display manager, the procedure will be different. Google is your friend. :-)
it seems that we will put
source ~/.bashrc
in our .bash_profile anyway. So why not just use one file, say .bashrc ?
Because there may be things you only want to do once per login (so in .bash_profile) rather than every time an xterm or the like opens (as per .bashrc), for example asking the user for a passphrase to decrypt and load SSH keys into an ssh agent, etc etc.
You can put some things in .bash_profile that are not appropriate for a shell instance that is not a terminal. For example, if you ran an external command from your editor through the shell - the shell instance would source .bashrc but not .bash_profile. For example, I might put alias ls=ls -F in my profile, but you wouldn't want that alias applied for just any instance of the shell, just ones you would interact with.