I started learning Linux shell scripting, when I was writing this script I got an error,
./my_script: 4: read: Illegal option -n
./my_script: 5: ./my_script: [[: not found
I found out its because #!/bin/sh line, i can still run the script without that line but it won't execute codes such as /n
#!/bin/sh
# Shell installer for gurb customizer. by Naveen Gamage.
OS=$(lsb_release -si)
ARCH=$(uname -m | sed 's/x86_//;s/i[3-6]86/32/')
VER=$(lsb_release -sr)
grabninstall() {
sudo add-apt-repository ppa:danielrichter2007/grub-customizer
sudo apt-get update
sudo apt-get install grub-customizer
}
echo "Installer for GRUB CUSTOMIZER\n"
echo "GURB CUSTOMIZER"
echo "A tool for editing and configuring boot menu (GRUB2/BURG).\n"
read -p "Do you want to install Grub Customizer for $OS ${VER} [$ARCH] ? (Y/n) " -n 1
if [[ $REPLY =~ ^[Yy]$ ]]
then
echo "The installer is downloading and installing GRUB Customizer!";
echo "This action may require your password.\n";
grabninstall
else
echo "user quit"
echo "Installation was unsuccessful."
fi
I'm doing this on Ubuntu 12.10.
and which sh gives this output
/bin/sh
any idea where i did wrong?
The problem is that you are using /bin/sh to run the script and on your system /bin/sh -> dash. This means that dash is executing your script. The dash shell does not support [[, but bash does. So you should change the first line in your script (called the Shebang) from #!/bin/sh to #!/bin/bash.
Alternatively, don't use [[ in your script. Only use features support by dash.
Also see this Ubuntu page on what constructs are not supported in dash.
Related
I am trying to compare strings in bash. I already found an answer on how to do it on stackoverflow. In script I am trying, I am using the code submitted by Adam in the mentioned question:
#!/bin/bash
string='My string';
if [[ "$string" == *My* ]]
then
echo "It's there!";
fi
needle='y s'
if [[ "$string" == *"$needle"* ]]; then
echo "haystack '$string' contains needle '$needle'"
fi
I also tried approach from ubuntuforums that you can find in 2nd post
if [[ $var =~ regexp ]]; then
#do something
fi
In both cases I receive error:
[[: not found
What am I doing wrong?
[[ is a bash-builtin. Your /bin/bash doesn't seem to be an actual bash.
From a comment:
Add #!/bin/bash at the top of file
How you are running your script?
If you did with
$ sh myscript
you should try:
$ bash myscript
or, if the script is executable:
$ ./myscript
sh and bash are two different shells. While in the first case you are passing your script as an argument to the sh interpreter, in the second case you decide on the very first line which interpreter will be used.
Is the first line in your script:
#!/bin/bash
or
#!/bin/sh
the sh shell produces this error messages, not bash
As #Ansgar mentioned, [[ is a bashism, ie built into Bash and not available for other shells. If you want your script to be portable, use [. Comparisons will also need a different syntax: change == to =.
if [ $MYVAR = "myvalue" ]; then
echo "true"
else
echo "false"
fi
I had this problem when installing Heroku Toolbelt
This is how I solved the problem
$ ls -l /bin/sh
lrwxrwxrwx 1 root root 4 ago 15 2012 /bin/sh -> dash
As you can see, /bin/sh is a link to "dash" (not bash), and [[ is bash syntactic sugarness. So I just replaced the link to /bin/bash. Careful using rm like this in your system!
$ sudo rm /bin/sh
$ sudo ln -s /bin/bash /bin/sh
If you know you're on bash, and still get this error, make sure you write the if with spaces.
[[1==1]] # This outputs error
[[ 1==1 ]] # OK
Specify bash instead of sh when running the script. I personally noticed they are different under ubuntu 12.10:
bash script.sh arg0 ... argn
Execute in your terminal:
sudo update-alternatives --install /bin/sh sh /bin/bash 100
Make the file executable and then execute without sh.
make it executable by $ chmod +x filename
then instead of sh filename use ./filename
I am getting this error:
[[: command not found
Here is my code:
#!/usr/bin/env bash
IS_PYSTACHE_INSTALLED=$(pip list --format=columns | grep "pystache ")
if [[ ! -z "${IS_PYSTACHE_INSTALLED}" ]]; then
echo " > Installing pystache"
pip install pystache
else
echo " > Pystache is already installed"
fi
What am I doing wrong?
if you are unsure of your default shell, go to the terminal and do a echo $SHELL, if you see #/bin/bash then chmod your script and run it like this ./filename.sh but make sure your hashbang line is #!/usr/bin/env bash. If you want to change your default shell to bash use the chsh command
I have a script starting with:
#!/usr/bin/sudo bash
It does a non instant processing and is not meant to be interrupted, so I would like to add the -b option to sudo to run it in background after the password has been entered.
#!/usr/bin/sudo -b bash
However, the script does not accept the option. Am I doing something wrong ? Can one even pass an option that way ? And if not, why ?
Thank you in advance.
Let's ask shellcheck:
$ shellcheck yourscript
In yourscript line 1:
#!/usr/bin/sudo -b bash
^-- SC2096: On most OS, shebangs can only specify a single parameter.
A fair workaround is to have the script invoke itself with sudo based on a flag:
#!/bin/bash
if [[ $1 == "-n" ]]
then
echo "Processing as $(whoami)"
else
printf "Option -n not specified: invoking sudo -b %q -n:" "$0"
exec sudo -b "$0" -n
fi
This has the additional benefit of letting you run yourscript -n directly to not invoke sudo and not run in the background. This allows things like sudo yourscript -n && mail -s "Processing complete" you#example.com which would not be possible if the script unconditionally backgrounded itself.
Caveat: sudo "$0" is not a bullet proof way of reinvoking the current script.
I'm getting started with bash scripting and made this little script following along a short guide but for some reason when I run the script with sh myscript I get
myscript: 5: myscript: 0: not found running on ubuntu 12.04
here is my script below I should at least see the echo message if no args are set:
#!/bin/bash
#will do something
name=$1
username=$2
if (( $# == 0 ))
then
echo "##############################"
echo "myscript [arg1] [arg2]"
echo "arg1 is your name"
echo "and arg2 is your username"
fi
var1="Your name is ${name} and your username is ${username}"
`echo ${var1} > yourname.txt`
`echo ${var1} > yourname.txt`
Get rid of the backticks.
echo ${var1} > yourname.txt
...for some reason when I run the script with sh myscript...
Don't run it that way. Make the script executable and run it directly
chmod +x myscript
./script
(or run with bash myscript explicitly).
It looks like that expression will work in bash but not in sh. As others pointed out change it to executable, make sure your shebang line is using bash and run it like this:
./myscript
If you want to run it with sh then it is complaining about line 5. Change it to this and it will work in /bin/sh.
if [ $# -ne 0 ]
Check out the man page for test.
Also you don't need the backticks on this line:
echo ${var1} > yourname.txt
I am trying to compare strings in bash. I already found an answer on how to do it on stackoverflow. In script I am trying, I am using the code submitted by Adam in the mentioned question:
#!/bin/bash
string='My string';
if [[ "$string" == *My* ]]
then
echo "It's there!";
fi
needle='y s'
if [[ "$string" == *"$needle"* ]]; then
echo "haystack '$string' contains needle '$needle'"
fi
I also tried approach from ubuntuforums that you can find in 2nd post
if [[ $var =~ regexp ]]; then
#do something
fi
In both cases I receive error:
[[: not found
What am I doing wrong?
[[ is a bash-builtin. Your /bin/bash doesn't seem to be an actual bash.
From a comment:
Add #!/bin/bash at the top of file
How you are running your script?
If you did with
$ sh myscript
you should try:
$ bash myscript
or, if the script is executable:
$ ./myscript
sh and bash are two different shells. While in the first case you are passing your script as an argument to the sh interpreter, in the second case you decide on the very first line which interpreter will be used.
Is the first line in your script:
#!/bin/bash
or
#!/bin/sh
the sh shell produces this error messages, not bash
As #Ansgar mentioned, [[ is a bashism, ie built into Bash and not available for other shells. If you want your script to be portable, use [. Comparisons will also need a different syntax: change == to =.
if [ $MYVAR = "myvalue" ]; then
echo "true"
else
echo "false"
fi
I had this problem when installing Heroku Toolbelt
This is how I solved the problem
$ ls -l /bin/sh
lrwxrwxrwx 1 root root 4 ago 15 2012 /bin/sh -> dash
As you can see, /bin/sh is a link to "dash" (not bash), and [[ is bash syntactic sugarness. So I just replaced the link to /bin/bash. Careful using rm like this in your system!
$ sudo rm /bin/sh
$ sudo ln -s /bin/bash /bin/sh
If you know you're on bash, and still get this error, make sure you write the if with spaces.
[[1==1]] # This outputs error
[[ 1==1 ]] # OK
Specify bash instead of sh when running the script. I personally noticed they are different under ubuntu 12.10:
bash script.sh arg0 ... argn
Execute in your terminal:
sudo update-alternatives --install /bin/sh sh /bin/bash 100
Make the file executable and then execute without sh.
make it executable by $ chmod +x filename
then instead of sh filename use ./filename