Text Processing Tools

File View commands: Cat, Tac,rev

Cat [OPTION] ... [FILE] ...

-E: Display line terminator $

-N: Numbering each line displayed

-A: Show all control characters

-B: Non-empty line number

-S: Compress consecutive blank lines into a row

Example: View the inside of a/etc/issue file and display the line number

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View the contents of a file on a page

MORE: Paging through files

More [OPTIONS ...] FILE ...

-D: Show page flipping and exit tips

Less: A page-by-page view of a file or stdin output

The commands that are useful for viewing are:

/Text Search text

n/n jumps to the next or previous match

Less command is a pager used by the man command

Show text before or after content

Head

Head [OPTION] ... [FILE] ...

-C #: Specify get before # bytes

-N #: Specifies the first # line to get

-#: Specify the number of rows

Tail

tail [OPTION] ... [FILE] ...

-C #: Specifies the # bytes after fetching

-N #: Specifies the # line after fetch

-#：

-F: Trace display File New additions, common log monitoring

Example: Show the first two lines of the/etc/passwd file, and the last two lines

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Extract text cut and merge files by column paste

Cut [OPTION] ... [FILE] ...

-D DELIMITER: Indicates delimiter, default tab

-F Fileds:

#: Section # Fields

#,#[,#]: Discrete multiple fields, such as 1,3,6

#-#: Multiple consecutive fields, such as 1-6

Mixed use: 1-3,7

-C cut by character

--output-delimiter=string specifying the output delimiter

Display a specified column of a file or stdin data

cut-d:-f1/etc/passwd

Cat/etc/passwd|cut-d:-f7

Cut-c2-5/usr/share/dict/words

Paste merge two files with row number columns to one line

Paste [OPTION] ... [FILE] ...

-D delimiter: Specify Delimiter, default tab

-S: All rows are composited on a single line display

Paste F1 F2

Paste-s F1 F2

Example: Remove the user name, UID, default shell in the/etc/passwd file

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Collecting text Statistics WC

Count words, total number of lines, total number of bytes, and total number of characters

Can run on data in a file or stdin

$wcstory. txt

392371901story.txt

Number of characters in the line number of digits

Use-l to count only the number of rows

Use-W to count only the total number of words

Use-C to count only the total number of bytes

Use-M to count only the number of characters

Example: Displays the number of lines, words, and characters of the/ETC/PASSW file

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Sorting text sort

Display the sorted text in stdout, without changing the original file

$sort [Options]file (s)

Common options

-R performs reverse direction (top to bottom) finishing

-N Execution by number size

The-f option ignores character capitalization in the (fold) string

-u option (unique) Delete duplicate rows in output

The-t C option uses C as the field delimiter

The-k x option can be used multiple times by using the C character delimited x column collation

Example: Sort the UID in a/etc/passwd file from large to small

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Uniq

Uniq command: Remove duplicate front and back rows from input

Uniq[option] ... [FILE] ...

-C: Shows the number of repetitions of each line;

-D: Show only the rows that have been repeated;

-U: Displays only rows that have not been duplicated;

Continuous and exactly the same side is repeated

Commonly used with the sort command:

Sort 1.txt | Uniq-c

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Text processing on Linux grep of the Three Musketeers

grep: Text filter (Pattern: pattern) tool;

grep, Egrep, fgrep (regular expression search not supported)

Grep:global Search RegularExpression and Print out of the line.

Function: Text Search tool, according to user-specified "mode" to match the target text line by row to check; print matching lines;

Patterns: Filter conditions written by regular expression characters and text characters

grep [OPTIONS] PATTERN [FILE ...]

grep root/etc/passwd

grep "$USER"/etc/passwd

grep ' $USER '/etc/passwd

grep ' WhoAmI '/etc/passwd

grep command Options

--color=auto: Coloring the text to match to the display;

-V: Displays rows that cannot be matched to pattern;

-I: Ignore character case

-N: Show matching line numbers

-C: Count the number of matching rows

-O: Displays only the matching string;

-Q: Silent mode, does not output any information

-A #:after, after # line

-B #: Before, Front # line

-c #:context, front and back # lines

-E: Implementing a logical or relationship between multiple options

Grep–e ' Cat '-e ' dog ' file

-W: Entire line matches Whole word

-E: Use ere

Character Matching:

. : matches any single character;

[]: matches any single character within the specified range

[^]: matches any single character outside the specified range

[:d Igit:], [: Lower:], [: Upper:], [: Alpha:], [: Alnum:], [:p UNCT:], [: Space:]

Number of matches: used after the number of characters to be specified, to specify the number of occurrences of the preceding character

*: matches the preceding character any time, including 0 times

Greedy mode: Match as long as possible

. *: Any character of any length

\?: match its preceding character 0 or 1 times

\+: Matches the preceding characters at least 1 times

\{m\}: Matches the preceding character m times

\{m,n\}: Matches the preceding character at least m times, up to N times

\{,n\}: Matches the preceding character up to n times

\{m,\}: Matches the preceding character at least m times

Example: Find the line in the/etc/rc.d/init.d/functions file that follows a word (including an underscore) followed by a parenthesis

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This article from "Progress a little every day" blog, declined reprint!

Text Processing Tools