Linux in a Nutshell, Fifth Edition

xor | 789

gawk

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Copyright © 2006 O’Reilly & Associates, Inc. All rights reserved.

toupper

toupper(str)

Translate all lowercase characters in str to uppercase and return the

new string.

while

while (condition)

statement

Do statement while condition is true (see if for a description of

allowable conditions). A series of statements must be put within

braces.

xor

xor(expr1, expr2) {G}

Return the bitwise XOR of expr1 and expr2, which should be

values that fit in a C unsigned long.

Output Redirections

For print and printf, dest-expr is an optional expression that directs the output to

a file or pipe.

> file

Direct the output to a file, overwriting its previous contents.

>> file

Append the output to a file, preserving its previous contents. In both this case

and the > file case, the file will be created if it does not already exist.

| command

Direct the output as the input to a system command.

|& command

Direct the output as the input to a coprocess. gawk only.

Be careful not to mix > and >> for the same file. Once a file has been opened with

>, subsequent output statements continue to append to the file until it is closed.

Remember to call close( ) when you have finished with a file, pipe, or coprocess. If

you don’t, eventually you will hit the system limit on the number of simulta-

neously open files.

printf Formats

Format specifiers for printf and sprintf have the following ...