How to use grep on column?

I want to apply grep on particular column in column command.

myfile.txt

3,ST,ST01,3,3,856
3,ST,ST02,4,9,0234
6,N1,N101,2,3,ST
6,N1,N102,1,60,Comcast
6,N1,N103,1,2,92

My Command:

column -s, -t < myfile.txt | grep -w "ST"

Here I want to only grep the pattern ST in 2nd column. How to do this ?

Expected Result:

3       ST            ST01              3            3            856
3       ST            ST02              4            9            0234

Answers:

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Method 1

Without doing some fancy RegEx where you count commas, you’re better off using awk for this problem.

awk -F, '$2=="ST"'

• The -F, parameter specifies the delimiter, which is set to a comma for your data.
• $2 refers to the second column, which is what you want to match on.
• "ST" is the value you want to match.

Method 2

Get ST in column 2 (-E and {1} can be omitted here):

grep -E '^([^,]*,){1}ST[^,]*' file

Output:

3  ST  ST01  3  3  856
3  ST  ST02  4  9  0234

Get ST in column 6:

grep -E '^([^,]*,){5}ST[^,]*' file | column -s, -t

Output:

6  N1  N101  2  3  ST

Method 3

By using awk we can select required column,

column -s, -t < myfile.txt | awk '$2 == "ST"'

If shell variable used,

seg="ST"
column -s, -t < $ST_FILE | awk -v var="$seg" '($2 == var)'

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0