Shell Operators; Console Shell Operators - DEC Digital Alpha VME 4/224 User Manual

12.1.3 Shell Operators

The UNIX command line makes use of some Bourne shell operators to complete a
command. In OpenVMS, some commands take parameters. The shell operators
are similar but are much more powerful because you can use them to combine
commands. These operators are described in Table 12–2.
Table 12–2 Console Shell Operators
Operator Name
> Output creation
>> Output append
< Input redirection
<< Here document
| Pipe
; Sequence
\ Line continuation
# Line comment
& Background
&a Affinity
Description
Writes output to a specified destination, such as a file.
Form: > destination
Adds output to the destination.
Form: >> destination
Reads input from the source.
Form: < source
Reads input from standard input until the specified
string is found at the beginning of a line.
Form: << string
Uses output of the first command as the input for the
second command.
Form: cmd1 | cmd2
Runs the first command to completion before running
second command.
Form: cmd1 ; cmd2
Continues the command on the next line. The prompt
changes to _> until the command is completed.
cmd1 \ _> cmd2
Form:
Ignores the text that follows the operator. Used for
embedding comments in command scripts or logs.
Form: # text
Runs the command in a background process. The
command line remains available for a new command.
Form: cmd &
Runs the process on the CPU allowed by the processor
affinity mask, m. Multiple processors can be specified
using a list or range.
Form: &a m
(continued on next page)
Console Primer 12–3