Question

I have a text file as input like this:let say it as xyz.txt

TIME    SR No               TYPE DATA

2.046103 1  1               Tx   d 8 01 01 01 99 9A 9B 9C 9D
2.046163 3  1               Rx   d 8 01 01 01 99 9A 9B 9C 9D
2.046361 2  1               Rx   d 8 01 01 01 99 9A 9B 9C 9D
2.046916 1  3               Tx   d 8 01 01 01 9B 9C 9D 9E 9F
2.046977 3  3               Rx   d 8 01 01 01 9B 9C 9D 9E 9F
2.047177 2  3               Rx   d 8 01 01 01 9B 9C 9D 9E 9F
2.048034 1  5               Tx   d 8 01 01 01 AD AE AF B0 B1
2.048095 3  5               Rx   d 8 01 01 01 AD AE AF B0 B1
2.048295 2  5               Rx   d 8 01 01 01 AD AE AF B0 B1
2.050006 1  8               Tx   d 8 01 01 01 B1 B2 B3 B4 B5
2.050065 3  8               Rx   d 8 01 01 01 B1 B2 B3 B4 B5
2.050265 1  8               Rx   d 8 01 01 01 B1 B2 B3 B4 B5
2.050632 2  601             Rx   d 8 01 01 01 CA CB CC CD CE
2.050690 3  700             Rx   d 8 01 01 01 CA CB CC CD CE
2.050887 1  700             Rx   d 8 01 01 01 CA CB CC CD CE

Requirement: I like to extract the first numeric strings (TIME) from lines that contains the SR “1” and TYPE as “Rx”

I hardly know perl and tried a command by reading on internet i.e:

perl -nle "print if /"1"\s(.+?)"Rx"/" xyz.txt >>output.txt

for extracting matched lines

The output i got in output.txt is:

2.046163 3  1               Rx   d 8 01 01 01 99 9A 9B 9C 9D
2.046361 2  1               Rx   d 8 01 01 01 99 9A 9B 9C 9D
2.050265 1  8               Rx   d 8 01 01 01 B1 B2 B3 B4 B5
2.050632 2  601             Rx   d 8 01 01 01 CA CB CC CD CE
2.050887 1  700             Rx   d 8 01 01 01 CA CB CC CD CE

Desired output(Requirement) are only these:

2.050265              
2.050887 

The complete information about above two value are from xyz.txt :

2.050265 1  8               Rx   d 8 01 01 01 B1 B2 B3 B4 B5
2.050887 1  700             Rx   d 8 01 01 01 CA CB CC CD CE

help me….what changes i need to do, so that it will satisfy:

a. consider only “1” from Rx row and not from No row in xyz.txt file.

b. Remove all except first string in output.txt

Answer 1

I would avoid regexes as being hard to maintain.

perl -lne '@a=split; print "$a[0]" if (($a[1] == 1) and ($a[3] eq "Rx"))'

Explanation:

• split — splits your line into tokens, separated by whitespace.
• print “$a[0]” — prints the first token
• $a[1] == 1 — evaluates if the 2nd token evaluates numerically to 1
• $a[3] eq “Rx” — evaluates if the 4th token equals the string Rx.

Also, the command line switches:

• -l causes perl to process lines similar to awk/sed (ignores leading/trailing whitespace)
• -n causes perl to apply the perl program to each line of input
• -e supplies the perl code to execute on the command line, as the next argument.