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Top Forums UNIX for Dummies Questions & Answers Redirection of file input to command Post 302856179 by wisecracker on Monday 23rd of September 2013 09:28:27 AM
Old 09-23-2013
Again longhand to demonstrate...
Code:
Last login: Mon Sep 23 14:05:22 on ttys000
AMIGA:barrywalker~> text="This is a line."
AMIGA:barrywalker~> echo -n "$text" > /tmp/txt
AMIGA:barrywalker~> read newtext < /tmp/txt
AMIGA:barrywalker~> echo "$newtext"
This is a line.
AMIGA:barrywalker~> # Use echo direct.
AMIGA:barrywalker~> echo < /tmp/txt

AMIGA:barrywalker~> # Nothing!
AMIGA:barrywalker~> # Now attempt to force into a variable.
AMIGA:barrywalker~> oldtext=$(echo < /tmp/txt)
AMIGA:barrywalker~> # Check "oldtext".
AMIGA:barrywalker~> echo "$oldtext"

AMIGA:barrywalker~> # Again nothing.
AMIGA:barrywalker~> # Now check the variable length.
AMIGA:barrywalker~> echo ${#oldtext}
0
AMIGA:barrywalker~> # As you can see no characters.
AMIGA:barrywalker~> _

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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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