exec - Invoke subprocess(es)

SYNOPSIS

DESCRIPTION

This command treats its arguments as the specification of one or more subprocesses to execute. The arguments take the form of a standard shell pipeline where each arg becomes one word of a command, and each distinct command becomes a subprocess.

If the initial arguments to exec start with - then they are treated as command-line switches and are not part of the pipeline specification. The following switches are currently supported:

-keepnewline

Normally a trailing newline will be deleted.

--

Marks the end of switches. The argument following this one will be treated as the first arg even if it starts with a -.

|

Separates distinct commands in the pipeline. The standard output of the preceding command will be piped into the standard input of the next command.

|&

Separates distinct commands in the pipeline. Both standard output and standard error of the preceding command will be piped into the standard input of the next command. This form of redirection overrides forms such as 2> and >&.

< fileName

The file named by fileName is opened and used as the standard input for the first command in the pipeline.

<@ fileId

FileId must be the identifier for an open file, such as the return value from a previous call to open. It is used as the standard input for the first command in the pipeline. FileId must have been opened for reading.

<< value

Value is passed to the first command as its standard input.

> fileName

Standard output from the last command is redirected to the file named fileName, overwriting its previous contents.

2> fileName

Standard error from all commands in the pipeline is redirected to the file named fileName, overwriting its previous contents.

>& fileName

Both standard output from the last command and standard error from all commands are redirected to the file named fileName, overwriting its previous contents.

>> fileName

Standard output from the last command is redirected to the file named fileName, appending to it rather than overwriting it.

2>> fileName

Standard error from all commands in the pipeline is redirected to the file named fileName, appending to it rather than overwriting it.

>>& fileName

Both standard output from the last command and standard error from all commands are redirected to the file named fileName, appending to it rather than overwriting it.

>@ fileId

FileId must be the identifier for an open file, such as the return value from a previous call to open. file, which must have been opened for writing.

2>@ fileId

FileId must be the identifier for an open file, such as the return value from a previous call to open. Standard error from all commands in the pipeline is The file must have been opened for writing.

>&@ fileId

FileId must be the identifier for an open file, such as the return value from a previous call to open. Both standard output from the last command and standard error from The file must have been opened for writing.

If standard output has not been redirected then the exec command returns the standard output from the last command in the pipeline. If any of the commands in the pipeline exit abnormally or are killed or suspended, then exec will return an error error messages describing the abnormal terminations; the errorCode variable will contain additional information about the last abnormal termination encountered. If any of the commands writes to its standard error file and that then exec will return an error; the error message about abnormal terminations (if any), followed by the standard error output.

If the last character of the result or error message is a newline then that character is normally deleted from the result or error message. normally end with newlines. However, if -keepnewline is specified then the trailing newline is retained.

executed in background. In this case the exec command will return a list whose elements are the process identifiers for all of the subprocesses in the pipeline. The standard output from the last command in the pipeline will redirected, and error output from all of standard error file unless redirected.

The first word in each command is taken as the command name; tilde-substitution is performed on it, and if the result contains no slashes then the directories in the PATH environment variable are searched for an executable by the given name. If the name contains a slash then it must refer to an executable reachable from the current directory. are performed on the arguments to commands.

KEYWORDS