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No Syntax Error and No Output

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Top Forums Shell Programming and Scripting No Syntax Error and No Output
# 1  
Old 05-17-2010
No Syntax Error and No Output
Hello All,

this script should use the command who, to log the Full Name, Date, and IP Address of the users who are connected to the system in a file called logfile. Excluding the user running the script.

the output in the log file is also sorted, id like to think my scripting is logical, but unfortunately i'm not getting any output in the logfile. and im not getting any syntax errors either.


Code:
        
        user=$(whoami | cut -d" " -f1 )
        who > temp
        lines=$(wc -l ./temp | cut -d" " -f1)
        cnt=1
        
        touch tmplog    
        touch logfile

        while [ $cnt -le $lines ]
        do
            usertemp=$(head -$cnt ./temp | tail -1 | cut -d" " -f1)
            nametemp=$(grep $usertemp /etc/passwd | cut -d: -f5)
            datetemp=$(head -$cnt ./temp | tail -1 | cut -d" " -f13)
            adrstemp=$(head -$cnt ./temp | tail -1 | cut -d" " -f14)

            if [ "$usertemp" != "$user" ]
            then 
                echo -n $nametemp >> tmplog
                echo -n " " >> tmplog
                echo -n $datetemp >> tmplog
                echo -n " " >> tmplog
                echo -n $adrstemp >> tmplog
                echo "" >> tmplog
            fi
            timetemp=$(head -$cnt ./temp | tail -1 | cut -d" " -f1)
            let cnt=$cnt+1             
        done        
        
        sort -db tmplog -o logfile
        rm temp
        rm tmplog

# 2  
Old 05-17-2010
Hi.

To begin, this won't work:
Code:
lines=$(wc -l ./temp | cut -d" " -f1)

The reason is that -d takes every occurrence to be a field separator.

wc -l returns multiple leading spaces (separators).

A quick change would be:
Code:
lines=$(wc -l ./temp | awk '{print $1}')

edit: silly me, see below Smilie
Last edited by Scott; 05-17-2010 at 03:54 PM..
This User Gave Thanks to Scott For This Post:
ibzee33
# 3  
Old 05-17-2010
or,
Code:
lines=$(wc -l < ./temp)

This User Gave Thanks to clx For This Post:
ibzee33
# 4  
Old 05-17-2010
A better way to loop through a file could be:
Code:
while read line
do
    usertemp=$(echo "$line" | cut -d" " -f1)
    nametemp=$(grep $usertemp /etc/passwd | cut -d: -f5)
    datetemp=$(echo "$line" | cut -d" " -f13)
    adrstemp=$(echo "$line" | cut -d" " -f14)

    if [ "$usertemp" != "$user" ]
    then 
        echo -n $nametemp >> tmplog
        echo -n " " >> tmplog
        echo -n $datetemp >> tmplog
        echo -n " " >> tmplog
        echo -n $adrstemp >> tmplog
        echo "" >> tmplog
    fi
done < ./temp

There should be better ways to do the job, can you post some lines of the file ./temp and the desired output?
This User Gave Thanks to Franklin52 For This Post:
ibzee33
# 5  
Old 05-17-2010
@scottn: i have a couple of questions,

what is this command, awk '{print $1}' is it compatible with Fedora?

what is the output for this?!
Code:
lines=$(wc -l < ./temp)

i used this command to save the number of lines, so i can use them in a loop while reading the file, a programming approach i guess, since im new to scripting and im not sure how to read the lines in a file
Code:
lines=$(wc -l ./temp | cut -d" " -f1)

@Franklin52
the ./temp file is only a temporary file holding the information from the who command, after that i read each line separately, and use it to save the full name, time and IP which i save in tmplog, that i sort and the final output is in logfile

the output should be something like this
Jack_Oneal 12:23 172.168.12.1
# 6  
Old 05-17-2010
Quote:
Originally Posted by ibzee33
@Franklin52
the ./temp file is only a temporary file holding the information from the who command
Ok, can you post the output of some lines?
# 7  
Old 05-17-2010
awk is an utility/language to process text data.its available on all modern unix based systems ( including fedora).

in your case, basically it gives you the first column of whatever you are getting from wc -l command.

Code:
/home/->wc -l log
14 log
/home/->wc -l log | awk '{print $1}'
14

same thing can be done with the indirection:
Code:
/home/->wc -l < log
14
/home/->


Next, Regarding reading of the file, yes,you don't need to count the lines and loop over it.

there is a built-in for this purpose. i.e read
Code:
while read line
do
 echo $line # do whatever with each line
done < ./temp

This User Gave Thanks to clx For This Post:
ibzee33
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