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deepblue_86
Asked: 2019-01-08 04:02:38 +0800 CST

How to read first four characters of file name?

  • 772

I have several files whose extensions are .gz with similar filenames to:

ANKR00TUR_R_20183350000_01D_30S_MO.crx.gz

I need to read the first four characters of these files' names and store these characters in a file. How can I do this?

scripts

2 Answers

  1. Best Answer

    Here the code to take first four character of filenames;

    filename=ANKR00TUR_R_20183350000_01D_30S_MO.crx.gz
tmp=${filename:0:4}
echo $tmp

    Result:

    echo "$tmp"

ANKR

    Source

    For a list

        for file in ./*.gz
    do
       echo "${file:2:4}" | tee -a list.txt
    done

    previous for cycle will print on the screen the result and also append to list.txt

    Source from Documentation on The Linux Documentation Project (TLDP)

    Update Improvement of code based on @steeldriver suggestion in comment.

    • 3

  2. To fetch the first N bytes of a string, cut can be used:

    echo ANKR00TUR_R_20183350000_01D_30S_MO.crx.gz | cut --bytes=1-4 > output

    This will extract the first 4 bytes from the given string and store it in the file output.

    To apply the above code to multiple filenames, use

    ls *.gz | cut --bytes=1-4 > output
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