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sudhirav 01-17-2011 11:41 PM

Shell script to check whether directory exists on remote server
 
Hi All,

I am new to scripting, would like to have a script that tests whether a directory exists on remote host & display the message accordingly. The remote hostname can be provided by means of file containing list of hostnames. Can use rsh for connecting to remote host.

I tried with couple of scripts by searching google but didn't get desired result. Please help me, below is my efforts, $file contains list of hostnames.

for i in $file
do
if ( [ `rsh $i test -d /tmp/.X*` ] || [ `rsh $i test -d /scratch/.X*` ] )
then
echo "directory exist"
else
exit 0;
fi
done

Thanks in advance, appreciate all the efforts.

zjoske 01-18-2011 02:39 AM

You have a very nice test if your remote server is up....

The command [ `rsh $i test -d /tmp/.X*` ] will always yield "0" when you are able to access the remote server.. It will not refect the value of the test command's result.

You'd probably want something like

[ `rsh $i "[[ -d /tmp/.X* ]] && echo true"` == "true" ]

Here you do the test if your directory is on your remote server and you pass the keyword true.
On your local server you check for the keyword.


Please note that the test on the remote server is ksh and does not necesary work on your server. I do not want to supply you with a proper solution, I just want to point out where your mistake is.

cin_ 01-18-2011 02:44 AM

results
 
test() seems fine...
Quote:

if ( [ `rsh $i test -d /tmp/.X*` ] || [ `rsh $i test -d /scratch/.X*` ] )
...you can write your if statement without the ( )
What are the results you are getting and what are the desired results?

sudhirav 01-18-2011 06:07 AM

Hi zjoske,

Thanks for the help, ran the script as per your suggestion getting following error :

#!/usr/bin/bash
if [ `rsh us01term4 "[[ -d /tmp/testsav ]] && echo true"`=="true" ]
then
echo "directory exists"
else
echo "directory doesn't exist"
fi

~/lsf_scripts % ./t.sh
[[: Command not found.
directory exists


The directory /tmp/testsav doesn't exist but the output displayed is "directory exists"/






Quote:

Originally Posted by zjoske (Post 4228363)
You have a very nice test if your remote server is up....

The command [ `rsh $i test -d /tmp/.X*` ] will always yield "0" when you are able to access the remote server.. It will not refect the value of the test command's result.

You'd probably want something like

[ `rsh $i "[[ -d /tmp/.X* ]] && echo true"` == "true" ]

Here you do the test if your directory is on your remote server and you pass the keyword true.
On your local server you check for the keyword.


Please note that the test on the remote server is ksh and does not necesary work on your server. I do not want to supply you with a proper solution, I just want to point out where your mistake is.


sudhirav 01-18-2011 06:19 AM

Hi

I would like to chek whether either /tmp/.X* or /scratch/.X* exists & if they do display message the directory exists accordingly.

Following is the script I run & output is as follows :

#!/usr/local/bin/bash
file=`~/lsf_scripts/bhosts_output`
for i in $file
do
if [[ `rsh $i test -d /tmp/.X*` ]] || [[ `rsh $i test -d /scratch/.X*` ]]
then
echo "directory exist"
else
echo "directory doesn't exit"
fi
done

#./p2.sh
/remote/ushome17/sav/lsf_scripts/bhosts_output: line 1: atto342: command not found
/remote/ushome17/sav/lsf_scripts/bhosts_output: line 2: atto343: command not found



For every hostname in the for loop for value of i an error command not found is displayed on the screen, nothing else. From the CLI I can do rsh or ping to the hosts atto342, atto343.

Quote:

Originally Posted by cin_ (Post 4228366)
test() seems fine...

...you can write your if statement without the ( )
What are the results you are getting and what are the desired results?


cin_ 01-18-2011 06:53 AM

try using Wrap [CODE]#[/CODE] tags for easy to read source
 
So for i in FILE it is going to go by each line in the file. If there is information, especially divided by a space ' ', then when bash reads it it will read the second piece as an argument or another command. So, I am thinking that is what is going on here: atto343: command not found.

Code:

...
if [[ `rsh "$i" test -d /tmp/.X*` ]] || [[ `rsh "$i" test -d /scratch/.X*` ]]
...

... might just solve that problem, or expose another...

Can you...
Code:

# cat FILE
... so I can see how the file is set up.

jschiwal 01-18-2011 07:46 AM

If rsh behavies like ssh, then:
ssh user@host "[ -d $DIR ]" && echo "dir exists"
will work.

Code:

DIRS="Documents Document Downloads Download"
for dir in $DIRS;
  do ssh elite "[ -d $dir ]" && echo "$dir exists" || echo "$dir doesn't exist"
done

Documents exists
Document doesn't exist
Downloads doesn't exist
Download exists

Your original thread tested different hosts for a directory. Not as easy for me to demonstrate with a real example.

You shouldn't be using rsh if your lan has a network connection. Ssh is a more secure replacement.
You can use:
eval $(ssh-agent)
ssh-add

to be able use public key authentication, and not have to enter the passphrase each time.

---
Be careful you understand when and where a variable is referenced.

This example will send the command verbatim to the server.
ssh user@host 'ls $HOME/Documents/'

This example will evaluate the variable $dir before executing the ssh command:
ssh user@host "ls $dir/*.pdf"

In my original example, the test "[ -d $dir ]" is made on the server after $dir is referenced on the client. The rest of the line runs on the client ( && echo "$dir exists" || echo "$dir doesn't exist" ).

zjoske 01-18-2011 08:55 AM

Hi Sudhirav,

If it does not work it might be the shell, try replacing "[[" with "[".

I am working with the kshell, it works both for me (this is just the test on the remote server):

==> with two brackets
zrh1lw01[teuniss] rsh zrh1l013 "[[ -f caramba ]] || echo false"
false
zrh1lw01[teuniss] rsh zrh1l013 "[[ -f superkaramba-0.39.tar.gz ]] || echo false"
zrh1lw01[teuniss]

==> with one bracket
zrh1lw01[teuniss] rsh zrh1l013 "[ -f superkaramba-0.39.tar.gz ] || echo false"
zrh1lw01[teuniss] rsh zrh1l013 "[ -f caramba ] || echo false"
false

If the test passes an retuns false in this case, you can process it in your script with an additional if statement.



Quote:

Originally Posted by sudhirav (Post 4228525)
Hi zjoske,

Thanks for the help, ran the script as per your suggestion getting following error :

#!/usr/bin/bash
if [ `rsh us01term4 "[[ -d /tmp/testsav ]] && echo true"`=="true" ]
then
echo "directory exists"
else
echo "directory doesn't exist"
fi

~/lsf_scripts % ./t.sh
[[: Command not found.
directory exists


The directory /tmp/testsav doesn't exist but the output displayed is "directory exists"/


zjoske 01-18-2011 09:10 AM

Sudhirav,

I wanted to show you what I meant with my statement that you ae doing a "connectivity" test

With test I can check if a file exists. You have to test the result by verifying the variable $?

zrh1lw01[teuniss] test -f caramba ; echo $?
1
zrh1lw01[teuniss] test -f superkaramba-0.39.tar.gz | echo $?
0

In the first case, the file caramba does not exist, the test failed
The file superkaramba-0.39.tar.gz does exist hence my variable $? is 0


However, doing this with ssh (or rsh, does not matter) on a remote server you will get

zrh1lw01[teuniss] ssh zrh1l013 test -f superkaramba-0.39.tar.gz | echo $?
0
zrh1lw01[teuniss] ssh zrh1l013 test -f caramba | echo $?
0

Why? It does not matter what the contents of $? on the remote machine is. The value of $? is on the local machine and reflects the status of ssh. The ssh command ran. Hence the value of "0" ...

cin_ 01-18-2011 11:27 AM

Special Characters
 
Bash Scripting Tutorial, Special Characters... http://tldp.org/LDP/abs/html/special-chars.html

Single and Double bracket explanation... http://tldp.org/LDP/abs/html/testcon....html#TTESTREF

Nominal Animal 01-18-2011 06:39 PM

Don't test. List and count:
Code:

for host in $list ; do
    count=`rsh $host "find /tmp /scratch -maxdepth 1 -type d -name '.X*' | wc -l"`
    if [ $count -gt 0 ]; then
        echo "$host: $count directories"
    else
        echo "$host: No directories"
    fi
done

Note that the counting is done on the remote machine, so only the command and the result is transferred.
Nominal Animal


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