Built-ins are used
in shell programs to make decisions and to add intelligence to the task to be performed. Built-ins for the Bourne shell are listed in Tables 3.6 and 3.7. More information on the built-ins described in Table 3.6 is available in the Solaris online manual pages. The shell conditionals listed in Table 3.7 are described in this chapter. Each shell has its own set of built-ins, with the Bourne shell having the fewest. For this reason, it is the smallest and fastest of the three shells.
Table 3.6. Bourne Shell
Built-Ins
Built-In
Description
break
Exits
a for or while loop
continue
Continues the next
iteration of a for or while loop
echo
Writes arguments
on standard output
eval
Evaluates and
executes arguments
exec
Executes a
program. Executes in place of the current process so that exec does not create a new process
exit
Exits the shell
program
export
Creates a global
variable
priv
Sets or displays
privileges
read
Reads a line from
standard input
readonly
Changes a variable
to read-only
set
Sets shell
options
test
Evaluates
conditional expressions
times
Displays
execution times
trap
Manages
execution signals
umask
Sets default
security for files and directories
unset
Unsets a local
variable
wait
Waits for
a background process to complete
Table 3.7. Bourne Shell
Conditionals
Conditional
Description
if-then-else-fi
Tests a
condition and selects an action based on the results of the test
case-esac
Selects an action
based on the value of the variable
for-do-done
Repeats a sequence
of commands until a predetermined condition is met
while-do-done
Repeats a sequence
of commands until a test condition is no longer true
until-do-done
Repeats a sequence
of commands until a test condition
results in a successful status
