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?
Does your script reference /bin/bash or /bin/sh in its hash bang line? The default system shell in Ubuntu is dash, not bash, so if you have #!/bin/sh then your script will be using a different shell than you expect. Dash does not have the <<< redirection operator.
Make sure the shebang line is:
#!/bin/bash
or
#!/usr/bin/env bash
And run the script with:
$ ./script.sh
Do not run it with an explicit sh as that will ignore the shebang:
$ sh ./script.sh # Don't do this!
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.
Docker:
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"]
Solution:
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.
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
> $text
> EOF
^Cpunt!
do it the simpler way,
direc=$(basename `pwd`)
Or use the shell
$ direc=${PWD##*/}
Another reason to the error may be if you are running a cron job that updates a subversion working copy and then has attempted to run a versioned script that was in a conflicted state after the update...
On my machine, if I run a script directly, the default is bash.
If I run it with sudo, the default is sh.
That’s why I was hitting this problem when I used sudo.
In my case error is because i have put ">>" twice
mongodump --db=$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
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.
I run into an issue last week that drives me crazy. I wrote a BASH script which does a remote ssh connection to acamai and than performs a simple 'ls'. I want to redirect the 'ls' sdtout output to a given file.
While the script itself works like a charm when run manually, it does not while it runs via cron. The cronjob runs as root and each command works as expected expect the ssh command. My System is Gentoo Linux and cron is the old but gold vixie-cron.
To reduce the 200 LOC I put the basics herein which alone (as a single script) are enough to demonstrate the problem.
#!/bin/bash
PATH='/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/opt/bin'
#set -x
shopt -s lastpipe
exec 2>log.out
(ssh -i <path to key> -o HostKeyAlgorithms=+ssh-dss -o StrictHostKeyChecking=no <account#example.com> 'ls -r <path>') > '/root/listing.txt'
Even in -vvv debug mode of ssh I can see, that everything works...just except that I get no stdout output.
Than I tried something else that I found in another posting on the internet:
#!/bin/bash
PATH='/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/opt/bin'
#set -x
shopt -s lastpipe
exec 2>log.out
(ssh -T -i <path to key> -o HostKeyAlgorithms=+ssh-dss -o StrictHostKeyChecking=no <account#example.com> 'ls -r <path>' </dev/zero) > '/root/listing.txt'
Drawback here, I start a ssh session that I can't close and I guess its due to /dev/zero.
Another approach was to TEE Pipe the sub-shell of the ssh command...this worked for a short time ( and why not yet anymore ?!)
Now I'm clueless and need help. Cron has its PATH, uses BASH etc. Curious my boss did that with success with java (and he hates BASH...).
Any explanation and helpful tips are greatly welcome.
I have same issue, I make script for CRON and it gets output from remote SSH host.
If i run script manually - it works as should. But when CRON runs it - i get just a part of remote output.
I cant realise why its happening.
#!/bin/sh
pass=123
filelist=$(sshpass -p "$pass" ssh -q -tt -o StrictHostKeyChecking=no user#"10.10.10.10" "list")
filestring=$(echo "$filelist" | grep -Po "(\S+\s\S+\s+\d+\s\d{2}:\d{2}:\d{2}\s\d{4})\slist0\.lst")
filedate=${filestring% list0.lst}
echo $filedate
filestamp=$(date -d "$filedate" +"%s")
echo $filestamp
When i get echos in file via CRON - there are date from 0:00:00 - field with date (echo $filedate) is empty. But when i run manually - i get normal date with time...
It really bother me.
Help?
I found solution - add "-tt" to ssh command and all input goes to variable.
filelist=$(sshpass -p "$pass" ssh -q -tt -o StrictHostKeyChecking=no user#"10.10.10.10" "list")
I am trying to run boto-rsync
using script.sh:
#!/bin/bash
echo `date`
echo "start"
boto-rsync -d 2 -a <access key> -s <secure key> s3://db-dump/hourly/2013/ /mnt/dir
echo "stop"
It works perfectly fine.
But when I run this using crontab, it ignores boto-rsync line.
Can anybody help?
Nine times out of ten, when you have a problem where something runs fine until you put it into a cron script, the underlying issue is that the cron script is running as a different user (root, usually) and the environment is not set up to access the command in question. So try doing a "su" and then typing "boto-rsync" and see if it's able to find the command.
I got the solution for this.
We need to add python and location of file
#!/bin/bash
echo `date`
echo "start"
python <location of boto-rsync> -d 2 -a <access key> -s <secure key> s3://db- dump/hourly/2013/ /mnt/dir
echo "stop"
I tried many things today to have ssh start a screen session which executes a command. The goal is to run a command on a remote machine and to be able to see the output and to detach and reattach latter. I want to do it from within a script without any interaction except detaching the screen session to close. No satisfying solution so far.
ssh -t ${host} "\
source ~/.bashrc; \
echo \"done.\"; \
cd \"$exedir\"; \
if [ \$? -ne 0 ]; then \
echo \"could not cd into directory\"; \
exit 1; \
fi; \
echo \"executing remotexe.sh ...\"; \
screen -S "remotexe" -t "remotexe" -R "nice -n$prio ./remotexe.sh ${exeparams[#]}";"
Some of the problems I encounter are related to the strange ways to pass commands to screen/ssh/bash which interfere with arguments and options (I don't quite understand why they do not use -- to interpret whatever follows as commands with arguments). The above version almost works. The remaining difficulty is that commands in remotexe.sh (in particular make) obviously miss exports and definitions from .bashrc. This is why I tried to include the source ~/.bashrc. I tried to add similar commands or explicit exports to remotexe.sh but it behaves as if it was executed by /bin/sh. If I do a conventional ssh login I can immediately run the remotexe.sh script without error. I also tried adding shell -$SHELL to my .screenrc.
Where is the mistake in this solution? How can I correct it?
I haven't tested your code at all, and will not vouch for the sanity of this, but you definitely have a quoting error. Try:
ssh -t ${host} "
source ~/.bashrc;
echo done.;
cd \"$exedir\" || exit 1;
echo executing remotexe.sh ...;
screen -S remotexe -t remotexe -R nice -n$prio ./remotexe.sh ${exeparams[#]};"
I have a script like this?
command='scp xxx 192.168.1.23:/tmp'
su - nobody -c "$command"
The main shell didn't print any info.
How can I get output from the sub command?
You can get all of its output by just redirecting the corresponding output channel:
command='scp ... '
su - nobody -c "$command" > file
or
var=$(su - nobody -c "$command")
But if you don't see anything, maybe the diagnostics output of scp is disabled?
Is there a "-q" option somewhere in your real command?
You aren't actually running the scp. When you use the
VAR=value cmd ...
syntax, the VAR=value setting goes into the environment of cmd but it's not available in the current shell. The command after your -c is empty, or the previous value of $command if there was one.