Shell Programming Four Musketeers practice--grep

grep (Global search Regular expression (RE) and print out of the line, fully search regular expressions and print out the lines)
grep is a powerful text search tool that uses regular expressions to search for text and prints matching lines without modifying the original file contents.

The grep family of Unix includes grep, Egrep, and Fgrep. Egrep and Fgrep commands are only a small difference from grep. Egrep is the extension of grep, which supports more re metacharacters, and fgrep is fixed grep or fast grep, which regards all the letters as words, that is, the metacharacters in the regular expression represents the literal meaning back to itself, no longer special.

Linux uses the GNU version of grep. It is more powerful and can use the Egrep and FGREP functions with the-G,-e,-f command line Options

1. Remove the etc/passwd, with the root row, and display the line numbers of the rows in the/etc/passwd

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Use-N to display line numbers

grep can use--color=auto to display the keyword portion using color.

2. Reverse the selection of/etc/passwd in the root

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3. Display two rows above and below the specified line

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4. Display version Information-V

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5. if referenced by \< and \>, use the expression as a single word search-W

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6. Search for "I" in a case-sensitive manner

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7. Display the line "^" Starting with a character

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8. Displays the line "$" ending with a character

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9. Egrep

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Shell Programming Four Musketeers practice--grep