I do this in a script:
read direc <<< $(basename `pwd`)
and I get:
Syntax error: redirection unexpected
in an ubuntu machine
/bin/bash --version
GNU bash, version 4.0.33(1)-release (x86_64-pc-linux-gnu)
while I do not get this error in another suse machine:
/bin/bash --version
GNU bash, version 3.2.39(1)-release (x86_64-suse-linux-gnu)
Copyright (C) 2007 Free Software Foundation, Inc.
Why the error?
I was getting this problem from my Dockerfile as I had:
RUN bash < <(curl -s -S -L https://raw.githubusercontent.com/moovweb/gvm/master/binscripts/gvm-installer)
However, according to this issue, it was solved:
The exec form makes it possible to avoid shell string munging, and to
RUN
commands using a base image that does not contain/bin/sh
.Note
To use a different shell, other than
/bin/sh
, use the exec form passing in the desired shell. For example,RUN ["/bin/bash", "-c", "echo hello"]
RUN ["/bin/bash", "-c", "bash < <(curl -s -S -L https://raw.githubusercontent.com/moovweb/gvm/master/binscripts/gvm-installer)"]
Notice the quotes around each parameter.
In my case error is because i have put ">>" twice
mongodump --db=$DB_NAME --collection=$col --out=$BACKUP_LOCATION/$DB_NAME-$BACKUP_DATE >> >> $LOG_PATH
i just correct it as
mongodump --db=$DB_NAME --collection=$col --out=$BACKUP_LOCATION/$DB_NAME-$BACKUP_DATE >> $LOG_PATH
If you're using the following to run your script:
sudo sh ./script.sh
Then you'll want to use the following instead:
sudo bash ./script.sh
The reason for this is that Bash is not the default shell for Ubuntu. So, if you use "sh" then it will just use the default shell; which is actually Dash. This will happen regardless if you have #!/bin/bash
at the top of your script. As a result, you will need to explicitly specify to use bash
as shown above, and your script should run at expected.
Dash doesn't support redirects the same as Bash.
You can get the output of that command and put it in a variable. then use heredoc
. for example:
nc -l -p 80 <<< "tested like a charm";
can be written like:
nc -l -p 80 <<EOF
tested like a charm
EOF
and like this (this is what you want):
text="tested like a charm"
nc -l -p 80 <<EOF
$text
EOF
Practical example in busybox
under docker
container:
kasra@ubuntu:~$ docker run --rm -it busybox
/ # nc -l -p 80 <<< "tested like a charm";
sh: syntax error: unexpected redirection
/ # nc -l -p 80 <<EOL
> tested like a charm
> EOL
^Cpunt! => socket listening, no errors. ^Cpunt! is result of CTRL+C signal.
/ # text="tested like a charm"
/ # nc -l -p 80 <<EOF
> $text
> EOF
^Cpunt!
On my machine, if I run a script directly, the default is bash
.
If I run it with sudo
, the default is sh
.
That’s why I was hitting this problem when I used sudo
.
do it the simpler way,
direc=$(basename `pwd`)
Or use the shell
$ direc=${PWD##*/}
Before running the script, you should check first line of the shell script for the interpreter.
Eg: if scripts starts with /bin/bash , run the script using the below command "bash script_name.sh"
if script starts with /bin/sh, run the script using the below command "sh script_name.sh"
./sample.sh - This will detect the interpreter from the first line of the script and run.
Different Linux distributions having different shells as default.
Another reason to the error may be if you are running a cron job that updates a subversion working copy and then has attempted to run a versioned script that was in a conflicted state after the update...
Source: Stackoverflow.com