SSH Agent Management Bash Command

.sagent

## SSH-Agent Manager

# Command list:
# sagent new - Generate new ssh-agent instance
# sagent [list] - List all ssh-agent instances along with keys they have loaded
# sagent <number> - Select ssh-agent instance based on number shown in sagent list
# sagent add </path/to/keyfile> - Add ssh key to currently selected ssh-agent
# sagent purgedead - Remove files related to dead ssh-agent instances


# Find existing sockets and store them in file_list
function sshagent_findsockets {
    file_list=()
    while IFS= read -r file ; do
        file_list=("${file_list[@]}" "$file")
    done < <(find /tmp -uid $(id -u) -type s -name agent.\* -printf "%T@ %Tc %p\n" 2>/dev/null | sort -n | awk '{print $9}')
}

# Print details of each socket in file_list
function sshagent_socketdetails {
    for agentsocket in ${!file_list[@]} ; do
        sshagent_testsocket ${file_list[$agentsocket]}
        if [ "$?" -eq "0" ]; then
            export SSH_AUTH_SOCK=${file_list[$agentsocket]}
            if [ "$SSH_AUTH_SOCK" == "$TMP_SSH_AUTH_SOCK" ]; then
                printf " *%s) SSH Agent [%s]: \n" "$agentsocket" "${file_list[$agentsocket]}"
            else
                printf "  %s) SSH Agent [%s]: \n" "$agentsocket" "${file_list[$agentsocket]}"
            fi
            while read -r ssh_key ; do
                printf "       %s\n" "$ssh_key"
            done <<< $(ssh-add -L | cut -d' ' -f 1,3)
            unset SSH_AUTH_SOCK
            unset ssh_key
        fi
    done
}

# Delete dead sockets in file_list
function sshagent_purgesockets {
    for agentsocket in ${!file_list[@]} ; do
        sshagent_testsocket ${file_list[$agentsocket]}
        if [ "$?" -eq "4" ]; then
            rm -rf ${file_list[$agentsocket]}
            printf "Deleted Agent [%s]: \n" "${file_list[$agentsocket]}"
        fi
    done
}

# Select socket from file_list or explicitly
function sshagent_selectsocket {
    IS_NUM='^[0-9]+$'
    if [ ! -x "$(which ssh-add)" ] ; then
        echo "ssh-add is not available; agent testing aborted"
        return 1
    fi

    if [[ "$1" =~ $IS_NUM ]] ; then
        export SSH_AUTH_SOCK=${file_list[$1]}
    else
        if [ X"$1" != X ] ; then
            export SSH_AUTH_SOCK=$1
        fi
    fi

    if [ X"$SSH_AUTH_SOCK" = X ] ; then
        return 2
    fi

    if [ -S $SSH_AUTH_SOCK ] ; then
        ssh-add -l > /dev/null
        if [ $? = 2 ] ; then
            echo "Socket $SSH_AUTH_SOCK is dead!  Deleting!"
            rm -f $SSH_AUTH_SOCK
            unset SSH_AGENT_PID
            unset SSH_AUTH_SOCK
            return 4
        else
            echo "ssh-agent $SSH_AUTH_SOCK"
            return 0
        fi
    else
        echo "$SSH_AUTH_SOCK is not a socket!"
        rm -f $SSH_AUTH_SOCK
        unset SSH_AGENT_PID
        unset SSH_AUTH_SOCK
        return 3
    fi
}

# Test if actually an active socket
function sshagent_testsocket {
    if [ ! -x "$(which ssh-add)" ] ; then
        echo "ssh-add is not available; agent testing aborted"
        return 1
    fi

    if [ X"$1" != X ] ; then
        export SSH_AUTH_SOCK=$1
    fi

    if [ X"$SSH_AUTH_SOCK" = X ] ; then
        return 2
    fi

    if [ -S $SSH_AUTH_SOCK ] ; then
        ssh-add -l > /dev/null
        if [ $? = 2 ] ; then
            echo "Socket $SSH_AUTH_SOCK is dead!"
            unset SSH_AGENT_PID
            unset SSH_AUTH_SOCK
            return 4
        else
            unset SSH_AGENT_PID
            unset SSH_AUTH_SOCK
            return 0
        fi
    else
        echo "$SSH_AUTH_SOCK is not a socket!"
        unset SSH_AGENT_PID
        unset SSH_AUTH_SOCK
        return 3
    fi
}

# Primary command function
function sshagent_init {
    IS_NUM='^[0-9]+$'
    SSH_CHOICE=$1
    TMP_SSH_AUTH_SOCK=$SSH_AUTH_SOCK
    unset SSH_AUTH_SOCK

    # ssh agent sockets can be attached to a ssh daemon process or an
    # ssh-agent process.
    AGENTFOUND=0

    if [ "${SSH_CHOICE,,}" = "new" ]; then
        exec ssh-agent $SHELL
        unset TMP_SSH_AUTH_SOCK
        return
    fi

    if [ "${SSH_CHOICE,,}" = "add" ]; then
        if [ -n "$TMP_SSH_AUTH_SOCK" ]; then export SSH_AUTH_SOCK=$TMP_SSH_AUTH_SOCK ; fi
        ssh-add $2
        return
    fi

    if [ "${SSH_CHOICE,,}" = "list" ]; then
        sshagent_findsockets
        echo "SSH Agents Found:"
        sshagent_socketdetails
        if [ -n "$TMP_SSH_AUTH_SOCK" ]; then export SSH_AUTH_SOCK=$TMP_SSH_AUTH_SOCK ; fi
        return
    fi

    if [ "${SSH_CHOICE,,}" = "purgedead" ]; then
        sshagent_findsockets
        sshagent_purgesockets
        return
    fi

    if [[ -n "${SSH_CHOICE}" ]] && ! [[ "${SSH_CHOICE}" =~ $IS_NUM ]]; then
        echo "ERROR: ${SSH_CHOICE} is not a valid option."
        return
    fi

    if [[ -z "${SSH_CHOICE}" ]]; then
        sshagent_findsockets
        echo "SSH Agents Found:"
        sshagent_socketdetails
        if [ -n "$TMP_SSH_AUTH_SOCK" ]; then export SSH_AUTH_SOCK=$TMP_SSH_AUTH_SOCK ; fi
        return
    fi

    # If there is no agent in the environment, search /tmp for
    # possible agents to reuse before starting a fresh ssh-agent
    # process.
    if [ $AGENTFOUND = 0 ] ; then
        sshagent_findsockets
        if [ -n "${SSH_CHOICE}" ]; then
           if sshagent_selectsocket ${SSH_CHOICE} ; then AGENTFOUND=1 ; fi
        fi
        if [ -z "${SSH_CHOICE}" ] ; then
            echo "SSH Agents Found:"
            sshagent_socketdetails
        fi
    fi

    if [ -n "$TMP_SSH_AUTH_SOCK" ] && [ -z "$SSH_AUTH_SOCK" ]; then
        export SSH_AUTH_SOCK=$TMP_SSH_AUTH_SOCK
    fi

    # Finally, show what keys are currently in the agent
    if [ $AGENTFOUND = 1 ] ; then
        ssh-add -L | cut -d' '  -f 1,3
    else
        echo "No SSH agent selected."
    fi

    # Clean up
    unset agentsocket
    unset file_list
    unset TMP_SSH_AUTH_SOCK
    unset AGENTFOUND
    unset SSH_CHOICE
}

alias sagent="sshagent_init"