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Test Your Knowledge in Computers #660
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DOS uses a filesystem which supports 9.3 filenames: 9 characters for the filename and 3 characters for the extension.
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rbash(1) [linux man page]

RBASH(1)						      General Commands Manual							  RBASH(1)

NAME
rbash - restricted bash, see bash(1) RESTRICTED SHELL
If bash is started with the name rbash, or the -r option is supplied at invocation, the shell becomes restricted. A restricted shell is used to set up an environment more controlled than the standard shell. It behaves identically to bash with the exception that the follow- ing are disallowed or not performed: o changing directories with cd o setting or unsetting the values of SHELL, PATH, ENV, or BASH_ENV o specifying command names containing / o specifying a file name containing a / as an argument to the . builtin command o specifying a filename containing a slash as an argument to the -p option to the hash builtin command o importing function definitions from the shell environment at startup o parsing the value of SHELLOPTS from the shell environment at startup o redirecting output using the >, >|, <>, >&, &>, and >> redirection operators o using the exec builtin command to replace the shell with another command o adding or deleting builtin commands with the -f and -d options to the enable builtin command o using the enable builtin command to enable disabled shell builtins o specifying the -p option to the command builtin command o turning off restricted mode with set +r or set +o restricted. These restrictions are enforced after any startup files are read. When a command that is found to be a shell script is executed, rbash turns off any restrictions in the shell spawned to execute the script. SEE ALSO
bash(1) GNU Bash-4.0 2004 Apr 20 RBASH(1)

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rsh(1M) 						  System Administration Commands						   rsh(1M)

NAME
rsh, restricted_shell - restricted shell command interpreter SYNOPSIS
/usr/lib/rsh [-acefhiknprstuvx] [argument]... DESCRIPTION
rsh is a limiting version of the standard command interpreter sh, used to restrict logins to execution environments whose capabilities are more controlled than those of sh (see sh(1) for complete description and usage). When the shell is invoked, it scans the environment for the value of the environmental variable, SHELL. If it is found and rsh is the file name part of its value, the shell becomes a restricted shell. The actions of rsh are identical to those of sh, except that the following are disallowed: o changing directory (see cd(1)), o setting the value of $PATH, o pecifying path or command names containing /, o redirecting output (> and >>). The restrictions above are enforced after .profile is interpreted. A restricted shell can be invoked in one of the following ways: 1. rsh is the file name part of the last entry in the /etc/passwd file (see passwd(4)); 2. the environment variable SHELL exists and rsh is the file name part of its value; the environment variable SHELL needs to be set in the .login file; 3. the shell is invoked and rsh is the file name part of argument 0; 4. the shell is invoke with the -r option. When a command to be executed is found to be a shell procedure, rsh invokes sh to execute it. Thus, it is possible to provide to the end- user shell procedures that have access to the full power of the standard shell, while imposing a limited menu of commands; this scheme assumes that the end-user does not have write and execute permissions in the same directory. The net effect of these rules is that the writer of the .profile (see profile(4)) has complete control over user actions by performing guaranteed setup actions and leaving the user in an appropriate directory (probably not the login directory). The system administrator often sets up a directory of commands (that is, /usr/rbin) that can be safely invoked by a restricted shell. Some systems also provide a restricted editor, red. EXIT STATUS
Errors detected by the shell, such as syntax errors, cause the shell to return a non-zero exit status. If the shell is being used non- interactively execution of the shell file is abandoned. Otherwise, the shell returns the exit status of the last command executed. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ SEE ALSO
intro(1), cd(1), login(1), rsh(1), sh(1), exec(2), passwd(4), profile(4), attributes(5) NOTES
The restricted shell, /usr/lib/rsh, should not be confused with the remote shell, /usr/bin/rsh, which is documented in rsh(1). SunOS 5.11 1 Nov 1993 rsh(1M)

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