CODEWITHSUNDEEP
shellsftpexit-code
user2418733
user2418733

Reputation: 33

How to exit SFTP when cd command fails

Shell script for file transfer by SFTP is already written and working fine on AIX Version 6.1. I am developing ETL with SAP Data Services and real new to shell scripting. During unit testing, I provided non-existent target folder for SFTP to simulate a case if target folder name was changed by a user, but it did not fail after command cd and returned exit code 0, though echoing error message: Couldn't canonicalise: Failure. That makes ETL process not aware that file was not transferred. When I injected exit 1 in script, the ETL job caught the SFTP failure and failed itself, which is an expected behaviour.

My question is: How can I tweak existing shell script invoking SFTP command to exit with code 1?

Here is excerpt from script:

'#!/bin/sh

....

echo cd $TARGET_REMOTE_DIR>>$INPUT_FILE

echo put $TARGET_LOCAL_DIR$TARGET_FILE_NAME>>$INPUT_FILE

echo quit>>$INPUT_FILE

/usr/bin/sftp -b $INPUT_FILE $USER@$HOSTNAME

I echo $? variable right after command cd, it returns 0 when remote dir is spelled wrong. What I am thinking is probably checking in-line for existence of an error message after command cd and if its length is not 0 then exit with code 1.

Something like in pseudo code: 

error_msg = get_error_msg({cd $TARGET_REMOTE_DIR>>$INPUT_FILE})

if length(trim(error_msg)) <> 0 then
echo “Cannot change directory! Aborting…”

exit 1

fi

Any comments are appreciated.

Cheers!

With great help from Martin I have implemented this solution: Catching $? return code right after command /usr/bin/sftp and forcing to exit with caught error!

/usr/bin/sftp -b $INPUT_FILE $USER@$HOSTNAME

if [[ $? -ne 0 ]]; then
  " SFTP Error while accessing remote target directory! Error message"
  exit $?
fi

Thank you all! Great forum!

Upvotes: 3

Views: 7373

Answers (1)

Martin Prikryl
Martin Prikryl

Reputation: 202222

First, I assume, you are using OpenSSH sftp.

The OpenSSH sftp indeed aborts the script and exits with 1, when cd command fails.

So you problem is probably not with the SFTP script, but in a way you capture the exit code.

If you share details, how you capture the exit code, you may get more concrete answer.

As for your test with echo $?:
Where do you put echo $? command? To your SFTP script ($INPUT_FILE)? sftp does not have an echo command; and it cannot resolve $? either.

If you put it to the shell script like this:

echo cd $TARGET_REMOTE_DIR>>$INPUT_FILE
echo $?

it does not do, what you want. You are here just querying result of previous echo command, which is unlikely to ever fail.

Upvotes: 1

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