Shell Programming and Scripting

Do you always get

xxxx
yyy
zzz
blah
blah

i.e. 5 lines or does the number vary ?

Hi Vino,

The number of lines do vary

You get it twice because the same pattern occurs in the file 2 times. Will there be any difference in the pattern occurences?

Hi Vish,

I understand now. So if there's a difference in the pattern, it will output my desired output. Thanks.

Could you pls explain your code in details because i;m not familiar with sed ?

Code:

sed -n '/05T00NPQSMR1/,/*\{58\}/p' input

-n
By default SED will print all the lines it process . But we need only certain parts of the file . Use -n option to tell SED not to print lines by default.

/05T00NPQSMR1/,/*\{58\}/
Here we are specifying the range of address we need.
This will match from any line containing pattern 05T00NPQSMR1 till the line contains 58 asterisks.

p
p command is used to print any line that is matched by the above regular expression.

Code:

awk -v pat1="05T00NPQSMR1" -v pat2="^[*]{3,}" '$0~pat1,$0~pat2' awtest

-v is used to pass the shell variables to awk.

Work in the above code is done by $0~pat1,$0~pat2. $0 in awk means the line that was read from the file. There are actions and patterns in awk, for a matching pattern specified action is performed.

In this code, data between pattern1("05T00NPQSMR1") and pattern2([*]{3,} - 3 0r more *s) is selected. no action is specified as default action is to print the matched lines.

Please see man awk for more details.

pat2="^[*]{3,}"
Hi Vish,
Why does "^" and "[]" and "{}" symbolise in the code ?

In $0~pat1,$0~pat2, what does the "~" means ?