I wrote a simple bash script to create some directories, like so:
#!/bin/sh
PROJECT_DIR=$(cd "$(dirname "$0")" && pwd)
cd ${PROJECT_DIR} || exit 1
mkdir -p Website/{static/{cs,js},templates/{html,xhtml}}
However, after I run the script (./script.sh), the directory structure looks like this:
There is no syntax error in my script. When I try the mkdir command directly on the terminal, the directories are created correctly.
Why is the bash script run behaving this way?
I have a file named syscheck.sh in /system/0211/ and I want to rename it to checkone.sh.
How can I do it?
To do a rename in a bash script, you simply need to use the mv (move) command.
mv /system/0211/syscheck.sh /system/0211/checkone.sh
You can put this command inside a shell script myrenamescript.sh file like so:
#!/bin/bash
mv /system/0211/syscheck.sh /system/0211/checkone.sh
Now set the script as executable
chmod a+x myrenamescript.sh
Now you can run it:
./myrenamescript.sh
If I make a directory with mkdir -p, it causes problems with scripts
$ mkdir -p test2/test2
$ cd test2/test2
$ echo '#!/bin/sh
> echo hello' > hello.sh
$ ./hello.sh
bash: ./hello.sh: Permission denied
This is nothing to do with mkdir. You simply haven't given hello.sh executable permissions. You need the following:
chmod +x hello.sh
Check your permissions
Check the permissions on your directories and the script itself. There may be a problem there, although it's unlikely.
ls -lad test2/test2
ls -l test2/test2/hello.sh
You can always use the --mode flag with mkdir if your permissions aren't being set correctly for some reason. See chmod(1) and mkdir(1) for more information.
Execute the file directly
You can execute the script with Bash directly, rather than relying on a shebang line or the executable bit, as long as the file is readable by the current user. For example:
bash test2/test2/hello.sh
Change file permissions
If you can execute the file when invoked explicitly with Bash, then you just need to make sure your file has the execute bit set. For example:
chmod 755 test2/test2/hello.sh
When I change into a directory with the cd command, I lose the previous working directory, unless I remember it in my memory. Is there some handy method to go back quickly?
Demo:
$ cd ~/some_path
$ cd /another_path
$ command_to_go_back_to_some_path
You can go back to the last dir with cd -
You can also do this
$ pushd ~/some_path
$ pushd /another_path
$ popd
$ popd
As mentioned you can use cd -. The shell internally does a cd $OLDPWD.
For usage in a script, you could use the OLDPWD shell variable: it contains the previous working directory.
$ pwd
/home/username
$ cd /usr/bin
$ pwd
/usr/bin
$ cd "$OLDPWD"
$ pwd
/home/username
I prefer this over cd - in scripts because I don't have to suppress any output.
If you want to use it in a script and suppress the output, do this:
cd - > /dev/null
I'm writing a Bash script. I need the current working directory to always be the directory that the script is located in.
The default behavior is that the current working directory in the script is that of the shell from which I run it, but I do not want this behavior.
#!/bin/bash
cd "$(dirname "$0")"
The following also works:
cd "${0%/*}"
The syntax is thoroughly described in this StackOverflow answer.
Try the following simple one-liners:
For all UNIX/OSX/Linux
dir="$(cd -P -- "$(dirname -- "$0")" && pwd -P)"
Bash
dir="$(cd -P -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd -P)"
Note: A double dash (--) is used in commands to signify the end of command options, so files containing dashes or other special characters won't break the command.
Note: In Bash, use ${BASH_SOURCE[0]} in favor of $0, otherwise the path can break when sourcing it (source/.).
*For Linux, Mac and other BSD:
cd "$(dirname "$(realpath -- "$0")")";
Note: realpath should be installed in the most popular Linux distribution by default (like Ubuntu), but in some it can be missing, so you have to install it.
Note: If you're using Bash, use ${BASH_SOURCE[0]} in favor of $0, otherwise the path can break when sourcing it (source/.).
Otherwise you could try something like that (it will use the first existing tool):
cd "$(dirname "$(readlink -f -- "$0" || realpath -- "$0")")"
For Linux specific:
cd "$(dirname "$(readlink -f -- "$0")")"
*Using GNU readlink on BSD/Mac:
cd "$(dirname "$(greadlink -f -- "$0")")"
Note: You need to have coreutils installed
(e.g. 1. Install Homebrew, 2. brew install coreutils).
In bash
In bash you can use Parameter Expansions to achieve that, like:
cd "${0%/*}"
but it doesn't work if the script is run from the same directory.
Alternatively you can define the following function in bash:
realpath () {
[[ "$1" = /* ]] && echo "$1" || echo "$PWD/${1#./}"
}
This function takes 1 argument. If argument has already absolute path, print it as it is, otherwise print $PWD variable + filename argument (without ./ prefix).
or here is the version taken from Debian .bashrc file:
function realpath()
{
f=$#
if [ -d "$f" ]; then
base=""
dir="$f"
else
base="/$(basename -- "$f")"
dir="$(dirname -- "$f")"
fi
dir="$(cd -- "$dir" && /bin/pwd)"
echo "$dir$base"
}
Related:
How to detect the current directory in which I run my shell script?
How do I get the directory where a Bash script is located from within the script itself?
Bash script absolute path with OS X
Reliable way for a Bash script to get the full path to itself
See also:
How can I get the behavior of GNU's readlink -f on a Mac?
cd "$(dirname "${BASH_SOURCE[0]}")"
It's easy. It works.
The accepted answer works well for scripts that have not been symlinked elsewhere, such as into $PATH.
#!/bin/bash
cd "$(dirname "$0")"
However if the script is run via a symlink,
ln -sv ~/project/script.sh ~/bin/;
~/bin/script.sh
This will cd into the ~/bin/ directory and not the ~/project/ directory, which will probably break your script if the purpose of the cd is to include dependencies relative to ~/project/
The symlink safe answer is below:
#!/bin/bash
cd "$(dirname "$(readlink -f "${BASH_SOURCE[0]}")")" # cd current directory
readlink -f is required to resolve the absolute path of the potentially symlinked file.
The quotes are required to support filepaths that could potentially contain whitespace (bad practice, but its not safe to assume this won't be the case)
This script seems to work for me:
#!/bin/bash
mypath=`realpath $0`
cd `dirname $mypath`
pwd
The pwd command line echoes the location of the script as the current working directory no matter where I run it from.
There are a lot of correct answers in here, but one that tends to be more useful for me (making sure a script's relative paths remain predictable/work) is to use pushd/popd:
pushd "$(dirname ${BASH_SOURCE:0})"
trap popd EXIT
# ./xyz, etc...
This will push the source file's directory on to a navigation stack, thereby changing the working directory, but then, when the script exits (for whatever reason, including failure), the trap will run popd, restoring the current working directory before it was executed. If the script were to cd and then fail, your terminal could be left in an unpredictable state after the execution ends - the trap prevents this.
I take this and it works.
#!/bin/bash
cd "$(dirname "$0")"
CUR_DIR=$(pwd)
Get the real path to your script
if [ -L $0 ] ; then
ME=$(readlink $0)
else
ME=$0
fi
DIR=$(dirname $ME)
(This is answer to the same my question here: Get the name of the directory where a script is executed)
cd "`dirname $(readlink -f ${0})`"
Most answers either don't handle files which are symlinked via a relative path, aren't one-liners or don't handle BSD (Mac). A solution which does all three is:
HERE=$(cd "$(dirname "$BASH_SOURCE")"; cd -P "$(dirname "$(readlink "$BASH_SOURCE" || echo .)")"; pwd)
First, cd to bash's conception of the script's directory. Then readlink the file to see if it is a symlink (relative or otherwise), and if so, cd to that directory. If not, cd to the current directory (necessary to keep things a one-liner). Then echo the current directory via pwd.
You could add -- to the arguments of cd and readlink to avoid issues of directories named like options, but I don't bother for most purposes.
You can see the full explanation with illustrations here:
https://www.binaryphile.com/bash/2020/01/12/determining-the-location-of-your-script-in-bash.html
echo $PWD
PWD is an environment variable.
If you just need to print present working directory then you can follow this.
$ vim test
#!/bin/bash
pwd
:wq to save the test file.
Give execute permission:
chmod u+x test
Then execute the script by ./test then you can see the present working directory.