Sed

The Grymoire's tutorial on SED

Sed

Sed Command in Unix and Linux ExamplesProgramming and Tools Blog -

'Sed' Command #1

For each line in a given input file, transform the first occurrence of the word 'the' with 'this'. The search and transformation should be strictly case sensitive.

sed 's/\bthe\b/this/'

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'Sed' Command #2

For each line in a given input file, transform all the occurrences of the word 'thy' with 'your'. The search should be case insensitive, i.e. 'thy', 'Thy', 'tHy' etc. should be transformed to 'your'.

sed 's/\bthy\b/your/Ig'

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'Sed' Command #3

Given an input file, in each line, highlight all the occurrences of 'thy' by wrapping them up in brace brackets. The search should be case-insensitive.

sed 's/thy/{&}/Ig'

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'Sed' Command #4

Given n lines of credit card numbers, mask the first 2 digits of each credit card number with an asterisk (i.e., *) and print the masked card number on a new line. Each credit card number consists of four space-separated groups of four digits. For example, the credit card number 1234 5678 9101 1234 would be masked and printed as **** **** **** 1234.

sed 's/\(\d\{4\}\s\)\{2\}\(\d\{4\}\)/**** **** ****/g'

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'Sed' Command #5

Given an input file, with N credit card numbers, each in a new line, your task is to reverse the ordering of segments in each credit card number. Assume that the credit card numbers will have 4 space separated segments with 4 digits each.

If the original credit card number is 1434 5678 9101 1234, transform it to 1234 9101 5678 1434.

sed -E 's/([0-9]+) ([0-9]+) ([0-9]+) ([0-9]+)/\4 \3 \2 \1/'