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Full Discussion: Meaning of script with echo, -d, -f1, -f2
Top Forums UNIX for Dummies Questions & Answers Meaning of script with echo, -d, -f1, -f2 Post 302889857 by bakunin on Monday 24th of February 2014 06:50:49 AM
Old 02-24-2014
Quote:
Originally Posted by DK2014
Code:
COMMENTS=`echo $COMMENTS | sed s/#/\ /g`

In the 2nd line what is the meaning of "sed s/#/\ /g`".

This one is easy: "sed" is a programmable text filter. In this case it replaces every "#" with what follows after "\" (here it looks like a space, but it could be a tab either in the original) in the content of a variable "COMMENTS". The result of this substitution is then fed to the variable "COMMENTS" again. Let me add that it is simply idiotic to do it this way, because "#" is indeed the comment character (like "//" in C++), but sometimes it is used in quoted strings. On the folliwng the script would most probably do something you don't want to have done:

Code:
command1 # this is a comment
echo "but this: # is not"


Quote:
Originally Posted by DK2014
[code]
SUBJECT="$ENV -- Jobs in JE status that need attention"

In the 1st line what is the meaning of "--" & how it gets club with $ENV.
"ENV" is a variable where the path/filename to a configuration file for the shell is stored. In most cases something like:

Code:
ENV="~/.kshrc"
export ENV

is part of your profile. This means that the login shell, when it starts, should search for a file in your HOME directory ("~") named ".kshrc" and source that in. Usually "~/.kshrc" contains some settings you want your shell to have.

Here, a variable "SUBJECT" is set to contain the content variable "ENV" plus the fixed string " -- Jobs in JE status that need attention" concatenated. "--" has no special meaning here. This too is most probably not doing what it is supposed to do, but guessing what it should do is beyond my abilities.

I hope this helps.

bakunin
 

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LEARN ABOUT OSX

script

SCRIPT(1)						    BSD General Commands Manual 						 SCRIPT(1)

NAME

     script -- make typescript of terminal session

SYNOPSIS

     script [-akq] [-t time] [file [command ...]]

DESCRIPTION

     The script utility makes a typescript of everything printed on your terminal.  It is useful for students who need a hardcopy record of an
     interactive session as proof of an assignment, as the typescript file can be printed out later with lpr(1).

     If the argument file is given, script saves all dialogue in file.	If no file name is given, the typescript is saved in the file typescript.

     If the argument command is given, script will run the specified command with an optional argument vector instead of an interactive shell.

     The following options are available:

     -a      Append the output to file or typescript, retaining the prior contents.

     -k      Log keys sent to program as well as output.

     -q      Run in quiet mode, omit the start and stop status messages.

     -t time
	     Specify time interval between flushing script output file.  A value of 0 causes script to flush for every character I/O event.  The
	     default interval is 30 seconds.

     The script ends when the forked shell (or command) exits (a control-D to exit the Bourne shell (sh(1)), and exit, logout or control-D (if
     ignoreeof is not set) for the C-shell, csh(1)).

     Certain interactive commands, such as vi(1), create garbage in the typescript file.  The script utility works best with commands that do not
     manipulate the screen.  The results are meant to emulate a hardcopy terminal, not an addressable one.

ENVIRONMENT

     The following environment variable is utilized by script:

     SHELL  If the variable SHELL exists, the shell forked by script will be that shell.  If SHELL is not set, the Bourne shell is assumed.  (Most
	    shells set this variable automatically).

SEE ALSO

     csh(1) (for the history mechanism).

HISTORY

     The script command appeared in 3.0BSD.

BUGS

     The script utility places everything in the log file, including linefeeds and backspaces.	This is not what the naive user expects.

     It is not possible to specify a command without also naming the script file because of argument parsing compatibility issues.

     When running in -k mode, echo cancelling is far from ideal.  The slave terminal mode is checked for ECHO mode to check when to avoid manual
     echo logging.  This does not work when in a raw mode where the program being run is doing manual echo.

BSD
								 January 22, 2004							       BSD
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