I am beginner in linux and wondering about a shorter way to go a directory having same parent directory. Here I elaborate that.
dir1
- dir11
- dir12
- dir13
- dir14
Directory dir1 has sub-directories dir11,...,dir14. I am at directory dir13 and want to go to dir12. What is direct way to do this?
I can do
cd..
cd dir12/
But I am wondering whether I can do this in single step. Any ideas?
cd doesn't only take one directory to change to. You can provide a complete path to which you want to go.
You can simply type cd ../dir12
You can also go all nuts with cd ../dir12/../dir13/../dir14/..
Try also the following: type cd ..<press Tag twice>. This will list you all directories in the path you have given.
There are wildcards that cd can use. For example ~ is your home directory. cd ~ or just cd will change into your $HOME.
See man cd (in a terminal) for more.
Related
How can I fixs that problem meanwhie I fix last code Selenim
Selenium but I am take same error. And cd is not see the Desktop but I am in the Desktop.
Here ~ is equal to /home/levidonates so when you type cd ~/Selenium it's actually cd /home/levidonates/Selenium but the folder Selenium is in your folder Desktop, so you need to type :
cd ~/Desktop/Selenium
~ is a shorthand for your home directory, /home/levidomates. The directories you're accessing are under there, not under the root, /. That is, ~/Desktop is not the same as /Desktop.
Firstly I see which folder do you try to enter / at the beginning? this is not true method.
/ characters means top of all folders root level.
You should not confuse it with the root user's home folder.
cd: change directory
cd .. : Back to the previous folder or up folder.
Firstly You can check your home folder
echo $HOME
then you must be enter pwd
if the your home folder /home/levidomates/
you must only cd ~ command
than cd Desktop
You shouldn't use / at the beginning of folders
Your absolute way to Deskotp is not correct...You forgot /home/levidomates
So then it should be cd /home/levidomates/Desktop instead of cd /Desktop
I'm just curious, when I'm using the cd command in bash, commands
cd foobar
and
cd ./foobar
work in the same way. I understand, that ./ refers to the current catalogue directory, but why then does "cd foobar" work? Is it just default, that when I'm not writing ./ on the beginning, program adds it on its own, or is it more complicated?
The cd command in bash (somewhat indirectly, as described below) invokes the chdir() syscall, behavior of which is specified by POSIX. The cd shell comand itself also has a POSIX specification for its behavior, in perhaps more detail than is appropriate for an accessible/readable definition.
Yes, the default for all operations (not only chdir() but also fopen() and others) is the current working directory.
This isn't specific to bash, but is operating-system-level behavior: "Current working directory" is part of the metadata about each process tracked by the kernel, and impacts filesystem-level requests made to the kernel: Any program, in any language, can call chdir("foo") or open("foo", O_RDONLY), and behavior will be to look for foo in the current directory, as inherited from the parent process or modified with prior chdir() calls.
That said, for the purposes of bash, cd ./foo is more specific than merely cd foo: The former says that you explicitly want the foo subdirectory of the current working directory. In bash, if the CDPATH shell variable is set, then cd foo will look in all directories listed in it, whereas cd ./foo explicitly only asks for foo under the current working directory.
Try this experiment:
# setup
tempdir=$(mkdir -d "${TMPDIR:-/tmp}/cdpath-test.XXXXXX")
mkdir -p "$tmpdir/i-am-a-test-directory"
CDPATH=".:$tempdir"
# this works, because CDPATH is honored
cd /
cd i-am-a-test-directory
# this does not, because you're explicitly asking for a directory that does not exist
cd /
cd ./i-am-a-test-directory
# cleanup
rm -rf "$tempdir"
unset CDPATH
Ignoring the CDPATH environment variable for the time being, the name after cd is a directory path name. There are only two sorts of path name in Unix:
absolute names that begin with a /
relative names which don't start with a /
All relative names are treated by the kernel as relative to the current directory — as if the name was prefixed by ./.
If you have CDPATH set, it complicates the search, and it is then conceivable that cd somewhere and cd ./somewhere land you in different directories. A directory name with no leading / and with no leading . or .. component (where cd .hidden doesn't count — the leading component is .hidden— but cd ./visible or cd ../visible do count) is searched for using CDPATH.
For example, consider this tree structure (only directories shown):
. - current directory
./somewhere
./src
./src/somewhere
Suppose you have CDPATH=src:. Then cd somewhere will go to ./src/somewhere and cd ./somewhere will go (unsurprisingly) to ./somewhere. If you type a name such as cd src/somewhere, the cd command will search for a sub-directory /xyz/pqr/src/somewhere for each directory /xyz/pqr on CDPATH in turn. I perpetually use CDPATH (7 directories on my own machines; 14 on my work machines).
Rule of thumb: use CDPATH=:…whatever…
That puts the current directory first on the search path, and is usually the most sane behaviour.
A similar story applies to searching for ordinary external (non-aliased, non-function, non-builtin) commands. Command names that start with a slash are absolute pathnames; command names containing a slash are relative to the current directory; command names without a slash are searched for on $PATH.
What does cd - exactly do ? ( the change directory command, plus a dash )
I noticed that if I run it in my /home/user folder repeatedly it outputs either /home/user or /home, this changes if I run it from a different folder.
cd -
pop the last directory you were from the stack of directory. It's like hitting "back" on the browser.
Exemple :
you are in /user/alex
you can test that with :
pwd
that give you
/user/alex
then if you do
%cd project1/subfolder
%pwd
/user/alex/project1/subfolder
%cd subsubfolder
%pwd
/user/alex/project1/subfolder/subsubfolder
%cd -
pwd
/user/alex/project1/subfolder
cd -
pwd
/user/alex
NB : it's not going back a level upper in the folder hierarchy. it's going to the previous current folder. ( a level upper is cd .. ).
The syntax
cd -
allows you to switch back to the "last directory you were in when you changed to the current directory". Running the command twice allows you to switch back to the current directory (since the current directory would then become the "last directory you were in when you changed to the current directory").
This is very useful if you are in a very long directory which you don't want to type out over and over, and you go to another lengthy named directory. Instead of retyping it, you can just do a 'cd -', which is similar to how some people use the alt-tab (or command-tab) to switch between applications. This key combo shortcut lets you essentially toggle between the last two applications.
cd stands for Change Directory
It is used to navigate arond your folders
So if you're in /home/user and have a folder in that directory called 'top-secret', you would access it by typing:
cd /top-secret
I have found a part of script like this In xx.sh：
BUILD_BOOT=.
mkdir -p $BUILD_BOOT
Can anybody help to explain what's the script above for as the directory parameter is .?
-p is short for --parents - it creates the entire directory tree up to the given directory.
E.g., suppose there are no directories in your current directory.
If you execute:
mkdir a/b/c
It will fail, since you do not have an a subdirectory.
On the other hand
mkdir -p a/b/c
Will create the entire structure - a/b/c
mkdir -p means: create the directory and, if required, all parent directories. The fact that this makes little sense when the path is specified as ., so the current working directory, does not change this. Most likely the line where the path is defined is meant to be adapted as required.
In general: consult the linux manual pages for questions about commands and their options like this: man mkdir. A great source of information!
See mkdir.
It creates all the intermediate directories on the path to the final directory that do not already exist (as well as the final directory), and doesn't fail if the target directory already exists.
In context, it is pointless; if the BUILD_ROOT is the current directory, it already exists. At some time, the BUILD_ROOT must have been a longer path.
This is a basic question but I am struggling to find a decent solution. This is hindering my script from automation.
I have the following path.
/home/hassan/Dyna/ProjectSimulation
in project simulation I have 3 folders
friction time force
like
/home/hassan/Dyna/ProjectSimulation/friction
Now I have a file friction1.txt in this friction folder and I want to copy it to ProjectSimulation.
is it possible to avoid complete path and just one step down?
Also if I have to copy this friction1.txt to folder force, is there anyway to avoid the complete path.
I mean I have a subroutine but this is path dependent , whenever I run it , I have to run in the same folder and then copy my results so I can run only one instance of my simulation.
Experts please guide me.
PS: This is part of a 600 lines shell.
This comes across as so basic that I must have misunderstood something in your question.
If you want to refer to a parent directory, .. is the way to do that. So, if you want to copy friction1.txt to two places you just do
cp friction1.txt ..
cp friction1.txt ../force
All you need to take care of is making sure that CWD is
/home/hassan/Dyna/ProjectSimulation/friction
so that the references point at the right place.
You can temprarily change the current directory to ProjectSimulation, copy the file (cp friction/friction1.txt .), then change the path back to the original (so the rest of the script works as before)
Alternatively, you can use dirname to get he name of the parent directory and use that.
Change to the root dir of your known directory structure. Then do the copy operations with relative paths. Then change back to your dir where you came from.
Your friends are:
cd
cd -
or better:
pushd
popd
(see man bash)
I.e.
pushd /home/hassan/Dyna/ProjectSimulation
cp friction/friction1.txt .
cp friction/friction1.txt force
popd