Question

the more I learn bash the more questions I have, and the more I understand why very few people do bash. Easy is something else, but I like it.

I have managed to figure out how to test directories and there writablity, but have a problem the minute I try to do this with a remote server over ssh. The first instance testing the /tmp directory works fine, but when the second part is called, I get line 0: [: missing]’`

Now if I replace the \” with a single quote, it works, but I thought that single quotes turn of variable referencing ?? Can someone explain this to me please ? Assuming that the tmp directory does exist and is writable, here the script so far

#!/bin/bash
SshHost="hostname"
SshRsa="~/.ssh/id_rsa"
SshUser="user"
SshPort="22"
Base="/tmp"
Sub="one space/another space"

BaseBashExist="bash -c \"[ -d \"$Base\" ] && echo 0 && exit 0 || echo 1 && exit 1\""
SSHBaseExist=$( ssh -l $SshUser -i $SshRsa -p $SshPort $SshHost ${BaseBashExist} )
echo -n $Base
if [ $? -eq 0 ]
    then
        echo -n "...OK..."
    else
        echo "...FAIL"
        exit 1
fi
BaseBashPerm="bash -c \"[ -w \"$Base\" ] && echo 0 && exit 0 || echo 1 && exit 1\""
SSHBaseExist=$( ssh -l $SshUser -i $SshRsa -p $SshPort $SshHost ${BaseBashPerm} )
if [ $? -eq 0 ]
    then
        echo "...writeable"
    else
        echo "...not writeable"
fi

BaseAndSub="$Base/$Sub"
BaseAndSubBashExist="bash -c \"[ -d \"$BaseAndSub\" ] && echo 0 && exit 0 || echo 1 && exit 1\""
SSHBaseAndSubExist=$( ssh -l $SshUser -i $SshRsa -p $SshPort $SshHost ${BaseAndSubBashExist} )
echo -n $BaseAndSub
if [ $? -eq 0 ]
    then
        echo -n "...OK..."
    else
        echo "...FAIL"
        exit 1
fi
BaseAndSubBashPerm="bash -c \"[ -w \"$BaseAndSub\" ] && echo 0 && exit 0 || echo 1 && exit 1\""
SSHBaseAndSubPerm=$(  ssh -l $SshUser -i $SshRsa -p $SshPort $SshHost ${BaseAndSubBashPerm} )
if [ $? -eq 0 ]
    then
        echo -n "...writeable"
    else
        echo "...not writeable"
fi
exit 0

Answer 1

You are fine with single quotes in this context; by the time the script is seen by the remote bash, your local bash has already substituted in the variables you want to substitute.

However, your script is a total mess. You should put the repetitive code in functions if you cannot drastically simplify it.

#!/bin/bash

remote () {
    # most of the parameters here are at their default values;
    # why do you feel you need to specify them?
    #ssh -l "user" -i ~/.ssh/id_rsa -p 22 hostname "$@"
    ssh hostname "$@"
    # —---------^
    # if you really actually need to wrap the remote
    # commands in bash -c "..." then add that here
}

exists_and_writable () {
    echo -n "$1"

    if remote test -d "$1"; then
        echo -n "...OK..."
    else
        echo "...FAIL"
        exit 1
    fi

    if remote test -w "$1"; then
        echo "...writeable"
    else
        echo "...not writeable"
    fi
}

Base="/tmp"
# Note the need for additional quoting here
Sub="one\\ space/another\\ space"

exists_and_writable "$Base"

BaseAndSub="$Base/$Sub"

exist_and_writable "$BaseAndSub"

exit 0