How to process log file line by line?

Shell Programming and Scripting
1

Greetings, I'm new to this forum, also new to shell script

I have done some simple shell script before, like backup linux machine using rsync and crontab, but now I need to do some log analyzing, which is beyond my ability... so I'm going to seek for help in this forum, hope someone could give me some advice, please.

I would like to ask, how can I process the log line by line? I have to make a Shell Script read the log and do some analyzing line by line, What function can help on this case? (If theres some example of using that function would help me a lot)

Thanks in advance.

2

awk will process line by line by default.

awk '{print}' <file name> will process line by line giving you the option to add whatever process you need to execute on the all the lines.

Its best that you give us a exemple file with what you are looking to achieve (end result).

Also put whatever you think should be done.

3

You can use tools like awk, sed, perl....or just with a shell script:

while read line
do
  # Do something with $line....
done  < logfile
4

As I always say: There are always more than one way to do it!

You can use:

# Awk
awk '{print}' "<input file>" # As maverick72 commented

# Shell
while read line
do
echo "${line}"
done < "<input file>"

The analysis is with you! =o)

5

One of my project is to do traceroute log analyzing, if there is a result more than 200ms then the script has to output the current traceroute to another log file.

the traceroute log look like this:

HOST: ADMIN02                  Loss%   Snt   Last   Avg  Best  Wrst StDev
  1. 10.x.x.x                      0.0%     3    0.1   0.2   0.1   0.2   0.1
  2. 118.x.x.x                    0.0%     3    2.2   2.0   1.9   2.2   0.2
  3. 218.x.x.x                    0.0%     3    1.3   1.3   1.3   1.4   0.1
  4. 203.x.x.x                    0.0%     3    2.6   2.5   2.4   2.6   0.1

I have tried using sed and awk to cut out those useless information and output to a log file only contains the ping, like this:

0.1   0.2   0.1   0.2   0.1
2.2   2.0   1.9   2.2   0.2
1.3   1.3   1.3   1.4   0.1
2.6   2.5   2.4   2.6   0.1

but I stopped here and dont know how to check each value one by one.

Hope these information I provide would help.

Thanks.

6 
awk 'NR > 1 { for ( i=5; i <= NF; i++ ) if ( $i > 200 ) print $0 }' tracert.tmp
2. 118.x.x.x 0.0% 3 2.2 2.0 201.9 2.2 0.2
4. 203.x.x.x 0.0% 3 204.6 2.5 2.4 2.6 0.1

cat tracert.tmp 
HOST: ADMIN02 Loss% Snt Last Avg Best Wrst StDev
1. 10.x.x.x 0.0% 3 0.1 0.2 0.1 0.2 0.1
2. 118.x.x.x 0.0% 3 2.2 2.0 201.9 2.2 0.2
3. 218.x.x.x 0.0% 3 1.3 1.3 1.3 1.4 0.1
4. 203.x.x.x 0.0% 3 204.6 2.5 2.4 2.6 0.1

Modified two values from your exemple so mine would work