Using vi, awk, sed - erase / remove / cut Few First , Last Characters in all lines of Linux file

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I have a text file called dat.txt and it having some generic text characters in the first and last of every line. I wanted to remove these charcters. See different options by using vi, awk, sed.

Content of my input dat.txt file is

$ cat dat.txt

xml.1-CCJGL1-CCJGL1-CCJGL.rec

xml.1-BSDF0Q1-BW;LKJ1-BWP30Q.rec

xml.1-LKJ<MN1-1LKJMG1-1W13LG.rec

xml.1-2<MBMV1-NVNBVKJH21HMRE.rec

xml.1-2EW*&Y1-(878761-2AJKGY.rec

Using vi editor:

Open the file in vi and run following commands.

1. To remove 4 characters from the beginning of every lines of a file

:%s/^....//g

2. To remove 4 characters from the end of every lines of a file

:%s/....$//g

Using sed

1. Remove 4 characters from the beginning of every lines

$ sed -r "s/^(.{0})(.{4})//" dat.txt

1-CCJGL1-CCJGL1-CCJGL.rec

1-BSDF0Q1-BW;LKJ1-BWP30Q.rec

1-LKJ<MN1-1LKJMG1-1W13LG.rec

1-2<MBMV1-NVNBVKJH21HMRE.rec

1-2EW*&Y1-(878761-2AJKGY.rec

2. To remove 4 characters from the end of every lines of a file

$ sed -r "s/(.{0})(.{4})$//" dat.txt

xml.1-CCJGL1-CCJGL1-CCJGL

xml.1-BSDF0Q1-BW;LKJ1-BWP30Q

xml.1-LKJ<MN1-1LKJMG1-1W13LG

xml.1-2<MBMV1-NVNBVKJH21HMRE

xml.1-2EW*&Y1-(878761-2AJKGY

Using awk

1. Remove 4 characters from the beginning of every lines

$ awk 'sub("^....", "")' dat.txt

1-CCJGL1-CCJGL1-CCJGL.rec

1-BSDF0Q1-BW;LKJ1-BWP30Q.rec

1-LKJ<MN1-1LKJMG1-1W13LG.rec

1-2<MBMV1-NVNBVKJH21HMRE.rec

1-2EW*&Y1-(878761-2AJKGY.rec

2. Remove 4 characters from the end of every lines

$ awk 'sub("....$", "")' dat.txt

xml.1-CCJGL1-CCJGL1-CCJGL

xml.1-BSDF0Q1-BW;LKJ1-BWP30Q

xml.1-LKJ<MN1-1LKJMG1-1W13LG

xml.1-2<MBMV1-NVNBVKJH21HMRE

xml.1-2EW*&Y1-(878761-2AJKGY

Using Shell Script

1. Remove 4 characters from the beginning of every lines

$ while read LINE

do

      echo "$LINE"|cut -c5-

done < dat.txt

$ while read LINE

do

      echo ${LINE:4}

done < dat.txt

2. Remove 4 characters from the end of every lines

$ while read LINE

do

      echo "${LINE%????}"

done < dat.txt

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