Is it possible in bash to automatically cd into a directory even without typing cd?
E.g., I'd like to be able to cd into ./whatever when just typing the following into the terminal:
./whatever
Is there a way to achieve this with bash? I know that zsh supports this.
One of my thoughts was to catch the Is a directory error thrown by bash when just typing ./whatever and subsequently cd into that directory but I couldn't find out a way to do it.
Yes, just enable the shell option autocd:
shopt -s autocd
From the Bash Reference Manual:
autocd
If set, a command name that is the name of a directory is executed as if it were the argument to the cd command. This option is only used by interactive shells.
Related
I set up subl command in ~/bin
But I couldn't run the command subl unless I run bash in my terminal. I thought changing default shell from zsh to bash would fix it but it did not. I still have to run bash before subl and this is annoying.
What's the difference between default bash and command bash?
Why subl wouldn't work until I run bash and what should I do to make it work?
I've just started learning actual computer and I know these could be silly questions. Thanks a lot for your help.
TORIs-MacBook-Pro:~ taro$ echo $SHELL
/usr/local/bin/bash
TORIs-MacBook-Pro:~ taro$ subl --help
-bash: subl: command not found
TORIs-MacBook-Pro:~ taro$ bash
bash-5.0$ subl --help
Sublime Text build 3211
Execute ~/bin/subl
Your subl command located in ~/bin (very often equivalent to /home/user/bin) is probably not in zsh's PATH variable :
The command interpreter doesn't look everywhere on you computer when you execute a command, it has a few directories to search in. This list is stored in an environment variable called PATH. It contains something like this :
$ echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
In my case, ~/bin is not in the list, but I can add it for this session only executing PATH="$PATH:~/bin" or include it when zsh starts by adding this line to ~/.zshrc :
PATH="$PATH:~/bin"
Now my PATH is :
$ echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:~/bin
Change the default shell
I'm not sure how it works with macOS X, but on Linux to change the default shell you need to execute this command line :
$ chsh -s /bin/bash
NOTE : the argument following -s must be a path to an interpreter, like bash.
You can found its path with which bash for example.
Then just relaunch your terminal or log out and in.
important : see first comment below about the tilde expansion (thanks to #Charles Duffy)
I am trying to learn the basics of shell. I used vim editro for creating my own list of commands to be executed. Here is the way I created the code
vi mycommands
then inside this file I wrote
cd Documents
I am using macOS Catalina which has zsh by default but switched to bash
So when I write the following command in the terminal:
$ sh +x mycommands
It shows
+cd Documents
The Documents has some files and directories but it is not changing directory.Where am I going wrong?
Any help will be greatly appreciated.
Scripts run like sh myscript execute in a separate sub-shell, not the current shell. Changing directory inside a script will not cause your shell to change directory. If you want to change directory in your shell, you need to run the commands in your shell.
To do that, run:
. ./myscript (sh, bash) or source ./myscript (bash).
See this question.
I want to accomplish this:
[zsh]$ pwd
/home/user
*[zsh]$ bash # enter to a bash shell at the same time as `cd ~/Desktop`.
[bash]$ pwd
/home/user/Desktop
[bash]$ exit
[zsh]$ pwd
**/home/user
I would like to know if there is any way to enter to the unix shell at the same time as changing a directory to some specific path. It's important that:
Line * is supposed to be a single-line command for entering a shell and changing a directory,
After exist from any new shell, it's expected to return to the latest location as it was before entering to the shell, see line **.
Using subshells is also useful for changing the current working directory temporary:
% (cd ~/Desktop && bash)
One straightforward answer consists in using a bash configuration file switching to the proper directory. By creating a file ~/.my_bashrc containing a single line:
cd ~/Desktop
you can then just type:
bash --rcfile ~/.my_bashrc
in a terminal to open a new shell directly in the Desktop directory.
Of course you can add other commands in ~/.my_bashrc (aliases, etc.), like in any regular bashrc file.
Simply do this.
cd /home/user/Desktop && bash
This will try to change your current directory to /home/user/Desktop and if it succeeds changes the shell to bash else throws error.
I think answer of #hchbaw is a bit tricky. I've just found a more effective solution from run bash command in new shell and stay in new shell after this command executes. In my case I can use:
bash --rcfile <(echo "cd ~/Desktop")
You can use pushd and popd commands:
pushd ~/Desktop && bash ; popd
pushd in this case is like "remember and cd" - it adds new directory to the top of directory stack, making it current directory. Next you start bash and after you exit bash, popd takes you back to the directory remembered by pushd.
EDIT: changed && to ; for better error handling, as pointed out in comment.
i have a script that reads a file line by line
the code is
FILE=commands.txt
while read CMD; do
echo "$CMD"
done < "$FILE"
This code is stored in a script file vxm_alarm.sh
In Korn shell, this loop works perfectly, when i run the command vxm_alarm.sh. In bash however i get the following error
vxm_alarm.sh: syntax error at line 4: `done' unexpected
In Bash I'm executing the script using the command sh vxm_alarm.sh. what am i doing wrong? And why can't we execute a script simply by doing this in bash
chmod +x filename.sh
filename.sh
Your code works on my machine using GNU bash 4.1.5
Try adding a shebang to the top:
#!/bin/sh
FILE=commands.txt
while read CMD; do
echo "$CMD"
done < "$FILE"
If you run sh vxm_alarm.sh you are most likely not running Bash. Try sh --version - If you get anything other than a version string, it's not Bash. Try running bash vxm_alarm.sh instead.
To be able to run a script without a path before it it has to be in one of the directories listed in the PATH variable. For example, if
echo "$PATH"
prints
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
you can put filename.sh in /usr/local/sbin, /usr/local/bin, /usr/sbin, /usr/bin, /sbin or /bin and run it as simply filename.sh. If you want your script to be run from a directory not in the path, you have three choices:
Modify $PATH to include the directory where the script resides.
Run it with a relative or absolute path.
Create an alias or function pointing to the relative or absolute path.
I'd like to answer this part of your question:
why can't we execute a script simply by doing this in bash
chmod +x filename.sh
filename.sh
As others already pointed out in part, there are several things required for that to work:
execution rights (You ensured that with your chmod command)
the shebang, so the system knows what shell/interpreter to use
#!/bin/bash
(it is important to say bash if you want bash and not sh)
make sure the command is found. This is the case when its directory is found in PATH. However what you'd rather do in this case is specify the directory. For the current directory you can do it like this
./name-of-the-script
In contrast to DOS and (IIRC) the various Windows Command line interfaces, Unix systems usually don't have the current directory on the PATH. It is possible to add it, but discouraged due to severe implications on security.
I have a bash script like:
#!/bin/bash
echo Hello world!
How do I execute this in Terminal?
Yet another way to execute it (this time without setting execute permissions):
bash /path/to/scriptname
$prompt: /path/to/script and hit enter. Note you need to make sure the script has execute permissions.
cd to the directory that contains the script, or put it in a bin folder that is in your $PATH
then type
./scriptname.sh
if in the same directory or
scriptname.sh
if it's in the bin folder.
You could do:
sh scriptname.sh
This is an old thread, but I happened across it and I'm surprised nobody has put up a complete answer yet. So here goes...
The Executing a Command Line Script Tutorial!
Q: How do I execute this in Terminal?
The answer is below, but first ... if you are asking this question, here are a few other tidbits to help you on your way:
Confusions and Conflicts:
The Path
Understanding The Path (added by tripleee for completeness) is important. The "path" sounds like a Zen-like hacker koan or something, but it is simply a list of directories (folders) that are searched automatically when an unknown command is typed in at the command prompt. Some commands, like ls may be built-in's, but most commands are actually separate small programs. (This is where the "Zen of Unix" comes in ... "(i) Make each program do one thing well.")
Extensions
Unlike the old DOS command prompts that a lot of people remember, you do not need an 'extension' (like .sh or .py or anything else), but it helps to keep track of things. It is really only there for humans to use as a reference and most command lines and programs will not care in the least. It won't hurt. If the script name contains an extension, however, you must use it. It is part of the filename.
Changing directories
You do not need to be in any certain directory at all for any reason. But if the directory is not on the path (type echo $PATH to see), then you must include it. If you want to run a script from the current directory, use ./ before it. This ./ thing means 'here in the current directory.'
Typing the program name
You do not need to type out the name of the program that runs the file (BASH or Python or whatever) unless you want to. It won't hurt, but there are a few times when you may get slightly different results.
SUDO
You do not need sudo to do any of this. This command is reserved for running commands as another user or a 'root' (administrator) user. Running scripts with sudo allows much greater danger of screwing things up. So if you don't know the exact reason for using sudo, don't use it. Great post here.
Script location ...
A good place to put your scripts is in your ~/bin folder.
You can get there by typing
# A good place to put your scripts is in your ~/bin folder.
> cd ~/bin # or cd $HOME/bin
> ls -l
You will see a listing with owners and permissions. You will notice that you 'own' all of the files in this directory. You have full control over this directory and nobody else can easily modify it.
If it does not exist, you can create one:
> mkdir -p ~/bin && cd ~/bin
> pwd
/Users/Userxxxx/bin
A: To "execute this script" from the terminal on a Unix/Linux type system, you have to do three things:
1. Tell the system the location of the script. (pick one)
# type the name of the script with the full path
> /path/to/script.sh
# execute the script from the directory it is in
> ./script.sh
# place the script in a directory that is on the PATH
> script.sh
# ... to see the list of directories in the path, use:
> echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
# ... or for a list that is easier to read:
> echo -e ${PATH//:/\\n}
# or
> printf "%b" "${PATH//:/\\n}"
/usr/local/sbin
/usr/local/bin
/usr/sbin
/usr/bin
/sbin
/bin
2. Tell the system that the script has permission to execute. (pick one)
# set the 'execute' permissions on the script
> chmod +x /path/to/script.sh
# using specific permissions instead
# FYI, this makes these scripts inaccessible by ANYONE but an administrator
> chmod 700 /path/to/script.sh
# set all files in your script directory to execute permissions
> chmod +x ~/bin/*
There is a great discussion of permissions with a cool chart here.
3. Tell the system the type of script. (pick one)
Type the name of the program before the script. (Note: when using this method, the execute(chmod thing above) is not required
> bash /path/to/script.sh
...
> php /path/to/script.php
...
> python3 /path/to/script.py
...
Use a shebang, which I see you have (#!/bin/bash) in your example. If you have that as the first line of your script, the system will use that program to execute the script. No need for typing programs or using extensions.
Use a "portable" shebang. You can also have the system choose the version of the program that is first in the PATH by using #!/usr/bin/env followed by the program name (e.g. #!/usr/bin/env bash or #!/usr/bin/env python3). There are pros and cons as thoroughly discussed here.
Note: This "portable" shebang may not be as portable as it seems. As with anything over 50 years old and steeped in numerous options that never work out quite the way you expect them ... there is a heated debate. The most recent one I saw that is actually quite different from most ideas is the "portable" perl-bang:
#!/bin/sh
exec perl -x "$0" "$#"
#!perl
Firstly you have to make it executable using: chmod +x name_of_your_file_script.
After you made it executable, you can run it using ./same_name_of_your_file_script
Change your directory to where script is located by using cd command
Then type
bash program-name.sh
And yet one more way
. /path/to/script
What is the meaning of the dot?
If you are in a directory or folder where the script file is available then simply change the file permission in executable mode by doing
chmod +x your_filename.sh
After that you will run the script by using the following command.
$ sudo ./your_filename.sh
Above the "." represent the current directory.
Note!
If you are not in the directory where the bash script file is present then you change the directory where the file is located by using
cd Directory_name/write the complete path
command. Otherwise your script can not run.