Brace Expansion + New Line

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

Dear all,

This is my current iptables (with default policy = Accept) and no rules.
Code:

[root@racnode1 ~]# iptables -L -v
Chain INPUT (policy ACCEPT 77072 packets, 7890K bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 70306 packets, 129M bytes)
 pkts bytes target     prot opt in     out     source               destination         
[root@racnode1 ~]#

I have decided to allow only incoming network connection from my own subnet and hence

Code:

[root@racnode1 ~]# iptables -A INPUT -s 192.168.0.0/24 -j ACCEPT
[root@racnode1 ~]# iptables -L -v
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         
  178  9055 ACCEPT     all  --  any    any     192.168.0.0/24       anywhere            

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 186 packets, 316K bytes)
 pkts bytes target     prot opt in     out     source               destination         
[root@racnode1 ~]#

Noted that my default policy is still ACCEPT, hence I

Code:

[root@racnode1 ~]# iptables --policy INPUT DROP

===============================================================

Upon this, I have 2 issues

a) my iptables -L -v command can't display fully, i am stuck at below

Quote:
[root@racnode1 ~]# iptables -L -v
Chain INPUT (policy DROP 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
b) my ssh login is very slow

Quote:
login as: root
-- waited quite sometime before prompting me for password
===============================================================

If i removed revert the INPUT policy to ACCEPT, then everything will be fine as normal.

Why ?

Thanks and look forward to your advises.

Regards,
Noob ;(

I am brand new to Linux (as of yesterday) and would like to know if there is a fix or do I need a different mouse. If so, any recommendations? Thanks in advance, Alan

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...

Hi All,
We have some shell scripts which will send emails about backup, alerts etc using mail command. Example.
Code:

echo "Test Mail" | mail -s "Test" me@mydomain.com

I guess the above command just connect port number 25 of our mail server even if we do not define any port number. Now I would like add smtp port number as 587 in all of the bash scripts. I googled for this but could not get whatever I am expecting. So expecting your kind reply to define smtp port number as 587 in all of the bash scripts.

Thanks in advance.

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?

Hi Everybody.....
I'm new to this site and new to Linux ( Ubuntu 12.04) generally. I am an old goat mechanical engineer with years of electronic instrumentation design experience. I am connecting several of my old HP digital oscilloscopes and logic analyzers to a Ubuntu box via GPIB (ieee 488) interface. I have the interface working well using the open source ( Sourceforge) "Linux-GPIB" kernel module. I can remotely control the instruments using "Linux-GPIB"'s "ibterm" terminal utility. However "ibterm" doesn't provide a means to do a scope screen dump to a file. A guy on EEBLOG published a short C language 30 line source code to perfome this function. Unfortunately it isn't a package with makefile.am, makefile .in, configure etc which I understand I could compile using the typical ./config, make, checkinstall procedure. It is just the c source code text. Soooo.....do I use gcc directly? If so, how do I run gcc in a manner to be able to uninstall all the various files it will make? Or ?? What is the procedure for automake in this situation ? Or....? I'm kind of lost. Your suggestions would be helpful.
Cheers.
Alan Jacobs
Green Bay, Wisconsin USA

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

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 have two scripts, the aim of these two scripts is, to check whether a particular script is running or not, if it wont runs, then throw a mail.

How i Achieved this output is, I wrote first script.

I created an infinite while loop which performs below steps

1. It creates a touch file
2. Triggers the script which needs to be monitored if its working or not.
3. Removes the touch file.

If the second step fails, then the remove file command will not happen and the script will stuck there itself.

I created an another script which checks the creation time of the touch file and if it is more than ten minutes, it means the second step in the first script is hanged, which also means that particular script is not working.

So if the creation time is more than 2 minutes the second script will throw a mail.

Below are the two scripts.

Code:

#!/bin/ksh



userid="chansd"

filename="/apps/log/check.txt"

while true ;do
touch $filename
pass=`/apps/eDMZ/call_st.ksh $userid`
sleep 20
rm $filename
done

Below script checks the file creation time and throws email if it is older than 2 minutes
Code:

#!/bin/ksh


filename="/apps/log/check.txt"

if [ -f "${filename}" ]
then
if test "`find $filename -mmin +2`"
then
echo "script is not working ! Please act on it" | mail -s "Script  is not working" Example@mail.com
fi


else

        exit 1

fi

What im going to do is

1. I am going to run the first script in background so it runs forever.
2. I am going to run the second script in cron forevry 5 mins to check the file creation time.

3. So if the first script hangs . I will kill the process using process id and after the issue resolves with the inner script, I will run the main script again.

I am new to Linux, Please let me know if this approach will work as expected.