Getting The Last Background Pid

Hi all,

Been reading on stdin, stdout and stderr and encounter 2 questions, hope gurus here can advise.

0 = stdin
1 = stdout
2 = stderr

Code:

Sun Dec 21 03:53:42 SGT 2014 > cat test5.sh
#!/bin/bash

echo "Please enter value for name :"
read name
echo "Your name is $name."

echo "Next echo will be a syntax error"
ehco

Code:

Sun Dec 21 03:53:46 SGT 2014 > test5.sh 1> output.txt 2> error.txt
Noob

Sun Dec 21 03:54:56 SGT 2014 > cat output.txt
Please enter value for name :
Your name is Noob.
Next echo will be a syntax error

Sun Dec 21 03:55:23 SGT 2014 > cat error.txt
/home/alan/scripts/test5.sh: line 8: ehco: command not found
Sun Dec 21 03:55:26 SGT 2014 >

Which so far all is good and the correct way to output everything including error to a single file is

Code:

Sun Dec 21 03:59:14 SGT 2014 > test5.sh > output.txt 2>&1

Q1) How is a command being interpreted in linux , the sequence in which it is interpreted ? from left to right ? right to left ?

Shouldn't it be

Code:

test5.sh 2>&1 1>output.txt 
or 
test5.sh 2>&1>output.txt ?

Regards,
Noob

Hello all,
I am working on setting up a script to set certain things and install them on new installs of linux, however I am running into an issue with appending code onto the end of my .bashrc.

I am trying to append Code:

PS1='\033[1;32m[\A \u@\h \W]\033[0m$ '

into .bashrc and I have tried the following methods without success
Code:

echo PS1='\[\e[1;31m\][\A \u@\h \W]\$\[\e[0m\] ' >> /root/.bashrc
echo 'PS1='\[\e[1;31m\][\A \u@\h \W]\$\[\e[0m\] '' >> /root/.bashrc
echo 'PS1=\'\[\e[1;31m\][\A \u@\h \W]\$\[\e[0m\] \'' >> /root/.bashrc
echo "PS1='\[\e[1;31m\][\A \u@\h \W]\$\[\e[0m\] '" >> /root/.bashrc

as well as several others with not avail. the issue is that echo is interpreting the single quotes that I would like printed. I have tried escaping them with not luck. any ideas?

I have install vsftpd and start it , but when when to try it by "ftp localhost" , but not work , would advise what is wrong ? thanks


#ps -ef |grep ftp
Code:

root     29896     1  0 10:53 ?        00:00:00 /usr/sbin/vsftpd /etc/vsftpd/vsftpd.conf
root     29899 23821  0 10:53 pts/0    00:00:00 grep ftp

# ftp localhost
Code:

Connected to localhost (127.0.0.1).
421 Service not available.

I'm currently using the command below, to output the memory usage of a debian system in bash scripts.

Code:

memusage=$(memusage=$(/usr/bin/free | grep Mem | awk '{print $3/$2 * 100.0 "%"}' | cut -d "%" -f1);echo "$(printf "%0.0f\n" $memusage)") && echo Memory Usage is $memusage

Being new to Linux though, I just found out that Linux takes up a lof of memory and puts it in cached.

Code:

root@Client1:~# free -m
             total       used       free     shared    buffers     cached
Mem:           927        799        128          0         15        754
-/+ buffers/cache:         28        898
Swap:           99          0         99

So the first command will actually output that the memory usage is 87%, when in reality is not. Its actually thinking that the memory usage is high because its also counting the cached memory, as used memory.

How can I modify the first command not to consider cached memory, as used memory?

Thanks

I have setup postfix in Oracle Linux VM in virtualbox to test simple email sends that I am sending it to my personal email.

I have configured the following in main.cf file

myhostname = abc.testserver.org
myorigin = $myhostname
inet_interfaces = localhost
#relayhost = localhost.localdomain - I have this commented as of now, but I tried with the localhost.localdomain, IP address and none worked. I also do not have my ISP's server details and I also do not want to use it.

I checked the /var/log/maillog and I see the following

Code:

May  4 17:25:37 oim sendmail[31684]: t44LPbKA031684: from=root, size=72, class=0, nrcpts=1, msgid=<201505042125.t44LPbKA031684@localhost.localdomain>, relay=root@localhost
May  4 17:25:37 oim sendmail[31685]: t44LPbSn031685: from=<root@localhost.localdomain>, size=378, class=0, nrcpts=1, msgid=<201505042125.t44LPbKA031684@localhost.localdomain>, proto=ESMTP, daemon=MTA, relay=localhost.localdomain [127.0.0.1]
May  4 17:25:37 oim sendmail[31684]: t44LPbKA031684: to=abc@abc.com, ctladdr=root (0/0), delay=00:00:00, xdelay=00:00:00, mailer=relay, pri=30072, relay=[127.0.0.1] [127.0.0.1], dsn=2.0.0, stat=Sent (t44LPbSn031685 Message accepted for delivery)

I can also see the messages in /var/spool/mqueue/. The telnet to the localhost 25 port also works. Is any of the config settings wrong?

Thanks.

Code:

PREFIX=192.168.1
OCTET=1
while [ $OCTET -lt "255" ]; do
    echo -en "Pinging ${PREFIX}.${OCTET}..."
    ping -c1 -w1 ${PREFIX}.${OCTET} > /dev/null 2>&1
    if [ "$?" -eq "0" ]; then
       echo "OK"
    else
       echo "Failed"
    fi
    let OCTET=$OCTET+1
done

My question is, in the penultimate line, why is it OCTET, and not $OCTET, with a dollar before it, meaning, the variable?

What if it were written:
Code:

let $OCTET=$OCTET+1

Like in C++ (I think) or Python or whatever?

Hi All..

I need to give four lines of gap(Freespace) between two command outputs.

what i did was below

Code:

echo "" >>$LOG_DIR/$LOG_NAME
echo "" >>$LOG_DIR/$LOG_NAME
echo "" >>$LOG_DIR/$LOG_NAME
echo "" >>$LOG_DIR/$LOG_NAME
print "***************** LEVEL 2: Truncating  Tables: Success:  tables Truncated ***********************" >> $LOG/$LOG_NAME
echo "" >>$LOG_DIR/$LOG_NAME
echo "" >>$LOG_DIR/$LOG_NAME
echo "" >>$LOG_DIR/$LOG_NAME
echo "" >>$LOG_DIR/$LOG_NAME
# Run the load scripts.
echo "***************** LEVEL 3: Loading Dupe Check Tables: Success: Dupe Check tables Loaded***********************" >> $LOG/$LOG_NAME

Is there any better way of writing this command to leave multiple lines between two commands.

Please advise...

I have a hostlist and there are several hosts. I want to use ssh to connect to them. I want to see whether the host is available or not by the time length of ssh takes. If it take long than 5s (which means it is not available). Then stop it, and ssh to next host. Once a host is available, then output the name of host. I previously use nmap, but the IT security told it is not allowed to install it on the desktop on campus.
Code:

    HOSTS=`cat $host_list`
    for line in $HOSTS
    do 
    ssh -o ConnectTimeout=5s $line true >> /dev/null
    RESULT=$?
    if [ $RESULT -eq 0 ]
    then
    echo $line > succeed.txt
    else
    echo $line > fail.txt
    fi
    done

The above script is all I can do.
The problem is when it is failed, I want to redirect the error message
Code:

ssh: connect to host c28-0112-05.ad.mtu.edu port 22: No route to host

. But I still get the error message.

Hello everyone,

I recently started using "function" and "case" in linux but I came across a slight problem

My code:

Code:

function Return
{
echo $1
}

case "$1" in 
 ""       ) echo "give parameters please";;
 [0-9]*   ) echo "No numbers please";;
 *        ) Return;;

So whenever the first parameter is a simple word I would like it returned, but it seems like there is no returned string (empty space)

Also I know I can just write "echo $1" instead of Return, but I'd like to use a function for this.

Can anyone tell me why the function doesn't return $1? Thanks!

i need to complete this exercise but my code has some issues
HERE is the PRoblem:
Create a script that can accept ANY amount of numbers from the command line. Process the numbers one at a time, where numbers greater than 10 print “large”, numbers less than or equal to 10 print “small”
E.g. process 5 10 15 would print
small
small
large

and here is my code so far
if [ $@ -le "10" ]
then
echo "smaller"
else
echo "bigger"
shift
fi
if [ $@ -le "10" ]
then
echo "smaller"
else
echo "bigger"
shift
fi
if [ $@ -le "10" ]
then
echo "smaller"
else
echo "bigger"
shift
fi
if [ $@ -le "10" ]
then
echo "smaller"
else
echo "bigger"
shift
fi

any help would be greatly appreciated