Linux in a Nutshell, Fifth Edition

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Chapter 6: The Bash Shell and Korn Shell

This is the Title of the Book, eMatter Edition

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

Examples

The following examples show the first line of various statements

that might use a test condition:

while test $# -gt 0 While there are arguments...

while [ -n "$1" ] While there are nonempty arguments...

if [ $count -lt 10 ] If $count is less than 10...

if [ -d RCS ] If the RCS directory exists...

if [ "$answer" != "y" ] If the answer is not y...

if [ ! -r "$1" -o ! -f "$1" ] If the first argument is not a

readable file or a regular file...

time

time command

time [command]

Execute command and print the total elapsed time, user time, and

system time (in seconds). Same as the Unix command time (see

Chapter 3), except that the built-in version can also time other

built-in commands as well as all commands in a pipeline.

The second form applies to ksh93; with no command, the total

user and system times for the shell and all children are printed.

times

times

Print accumulated process times for user and system.

times

times

ksh93 alias for { {time;} 2>&1;}. See also time.

trap

trap [ [commands] signals]

trap -p

trap -l

Execute commands if any signals are received. The second form is

specific to Bash and ksh93; it prints the current trap settings in a

form suitable for rereading later. The third form is specific to Bash;

it lists all signals and their numbers, ...