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Linux in a Nutshell

This directory of Linux commands is from Linux in a Nutshell, 5th Edition.

Click on any of the 687 commands below to get a description and list of available options. All links in the command summaries point to the online version of the book on Safari Bookshelf.

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flex

flex [options] [file]

flex (Fast Lexical Analyzer Generator) is a faster variant of lex. It generates a lexical analysis program (named lex.yy.c) based on the regular expressions and C statements contained in one or more input files. See also bison, yacc, and the O'Reilly book lex & yacc.

Options

-b

Generate backup information to lex.backup.

-d

Debug mode.

-f

Use a faster scanner. The result is larger but faster.

-h

Help summary.

-i

Scan case-insensitively.

-l

Maximum lex compatibility.

-o file

Write output to file instead of lex.yy.c.

-p

Print performance report.

-s

Exit if the scanner encounters input that does not match any of its rules.

-t

Print to standard output. (By default, flex prints to lex.yy.c.)

-v

Print a summary of statistics.

-w

Suppress warning messages.

-B

Generate batch (noninteractive) scanner.

-F

Use the fast scanner table representation. This option is usually as fast as -f and often generates smaller data (although for some data sets, it generates larger data).

-I

Generate an interactive scanner (default).

-L

Suppress #line directives in lex.yy.c.

-P prefix

Change default yy prefix to prefix for all globally visible variable and function names.

-V

Print version number.

-7

Generate a 7-bit scanner.

-8

Generate an 8-bit scanner (default).

-+

Generate a C++ scanner class.

-C

Compress scanner tables but do not use equivalence classes.

-Ca

Align tables for memory access and computation. This creates larger tables but gives faster performance.

-Ce

Construct equivalence classes. This creates smaller tables and sacrifices little performance (default).

-Cf

Generate full scanner tables, not compressed.

-CF

Generate faster scanner tables, like -F.

-Cm

Construct metaequivalence classes (default).

-Cr

Bypass use of the standard I/O library; use read( ) system calls instead.