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deepblue_86
Asked: 2015-10-20 06:06:05 +0800 CST

Extracting part of a specific column in text file

  • 772
ffmj0010.09o:FFMJ                                                  MARKER NAME
ffmj0020.09o:BRMU                                                  MARKER NAME

In this text file (2 lines and no space between the lines) I need to extract 4 characters after ":" ("FFMJ", "BRMU") and save them in another text file. Which command do I need to use?

text-processing

4 Answers

  1. Best Answer

    Using sed:

    sed 's/.*:\(.\{4\}\).*/\1/' in > out
    • s: asserts to perform a substitution
    • /: stops the command / starts the pattern
    • .*:: matches any number of any character until the last : character and a : character
    • \(.\{4\}\): matches and groups 4 occurences of any character
    • .*: matches any number of any character
    • /: stops the pattern / starts the replacement string
    • \1: backreference replaced with the first captured group
    • /: stops the replacement string / starts the pattern flags

    Sample output on the example file:

    % cat in
ffmj0010.09o:FFMJ MARKER NAME
ffmj0020.09o:BRMU MARKER NAME
% sed 's/.*:\(.\{4\}\).*/\1/' in > out
% cat out
FFMJ
BRMU
    • 3

  2. If you are sure that you want exactly 4 characters before end of the line, you can do:

    grep -Eo '.{4}$' file.txt >out.txt

    Otherwise you can go for grep with PCRE to get all characters after : till the end of the line:

    grep -Po '.*:\K[^:]+$' file.txt >out.txt

    You can also use bash parameter expansion:

    while IFS= read -r line; do echo "${line##*:}"; done <file.txt >out.txt

    EDIT:

    As @kos pointed out I might have misunderstood the question, if you want exactly 4 characters after : you can do:

    grep -Po '.*:\K.{4}' file.txt >out.txt
    • 3

  3. Using awk and multiple delimiters

    awk -F'[: ]' '{print $2}' in > out

    Example

    $ cat in
ffmj0010.09o:FFMJ                                                  MARKER NAME
ffmj0020.09o:BRMU                                                  MARKER NAME

$ awk -F'[: ]' '{print $2}' in 
FFMJ
BRMU
    • 3

  4. Using grep:

    cat oldFile | grep -o ":[A-Z]*" | grep -o "[A-Z]*" > newFile

    cat oldFile |                                         # Read the file
               grep 
                    -o                                # Only give the greped data
                       ":[A-Z]*"                      # Find a : followed by 4
                                                      #  4 capital letters
                                 | grep -o "[A-Z]*"   # Remove the : from that

    Then the > newFile outputs to a file.

    On the example:

    ffmj0010.09o:FFMJ MARKER NAME
ffmj0020.09o:BRMU MARKER NAME

    goes to

    FFMJ
BRMU
    • 1