Simple linux script help

Question

I have a text file with the following structure:

text1;text2;text3;text4
...

I need to write a script that gets 2 arguments: the column we want to search in and the content we want to find.

So the script should output only the lines ( WHOLE LINES! ) that match content(arg2) found in column x(arg1).

I tried with egrep and sed, but I'm not experienced enough to finish it. I would appreciate some guidance...

Answer 1

Given your added information of needing to output the entire line, awk is easiest:

awk -F';' -v col=$col -v pat="$val" '$col ~ pat' $input

Explaining the above, the -v options set awk variables without needing to worry about quoting issues in the body of the awk script. Pre-POSIX versions of awk won't understand the -v option, but will recognize the variable assignment without it. The -F option sets the field separator. In the body, we are using a pattern with the default action (which is print ); the pattern uses the variables we set with -v for both the column ( $ there is awk 's "field index" operator, not a shell variable) and the pattern (and pat can indeed hold an awk -style regex).

Answer 2

cat text_file.txt| cut -d';' column_num | grep pattern

It prints only the column that is matched and not the entire line. let me think if there is a simple solution for that.

Answer 3

Python

 #!/usr/bin/env python
 import sys
 column = 1 # the column to search
 value = "the data you're looking for"
 with open("your file","r") as source:
    for line in source:
        fields = line.strip().split(';')
        if fields[column] == value:
             print line

Answer 4

grep -B1 -i "string from previous line" |grep -iv 'check string from previous line' |awk -F" " '{print $1}'

这将打印您的行。

Answer 5

There's also a solution with egrep . It's not a very beautiful one but it works:

egrep "^([^;]+;){`expr $col - 1`}$value;([^;]+;){`expr 3 - $col`}([^;]+){`expr 4 - $col`}$" filename

or even shorter:

egrep "^([^;]+;){`expr $col - 1`}$value(;|$)" filename