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Full Discussion: [Help] Grep, Variables, IF statements... Fun
Top Forums Shell Programming and Scripting [Help] Grep, Variables, IF statements... Fun Post 302770524 by JonLaberge on Saturday 16th of February 2013 10:58:53 PM
Old 02-16-2013
Code [Help] Grep, Variables, IF statements... Fun
Hello, this will be my first post. I've been browsing around for a bit and have found a lot of useful information on here, hopefully a solution can be provided to me.

Issue:

Alright, I am looking to search for strings within a file using variables.

I have a script that will accept 3 or 4 parameters, 3 is required 4th isn't mandatory.

I would like to search the text file for the 3 parameters matching within the same line, if they do match then I want to remove that line and replace it with my new one, basically it would update the 4th parameter if set, and avoid duplicate entries.


Currently this is what I have gotten:

input= egrep -e '$domain\s+$type\s+$item' ~/etc/security/limits.conf

if [ "$input" == "" ]; then

echo $domain $type $item $value >>~/etc/security/limits.conf

echo \"$domain\" \"$type\" \"$item\" \"$value\" has been successfully added to your limits.conf file.


else
cat ~/etc/security/limits.conf | egrep -v "$domain|$type|$item" >~/etc/security/limits.conf1
rm -rf ~/etc/security/limits.conf
mv ~/etc/security/limits.conf1 ~/etc/security/limits.conf

echo $domain $type $item $value >>~/etc/security/limits.conf

echo \"$domain\" \"$type\" \"$item\" \"$value\" has been successfully added to your limits.conf file.
exit 0
fi


Now I already know that the input=egrep etc.. will not work, it works if I hard code some values but it won't accept that variables. Basically I have domain=$1, type=$2 and so on.

I would like it so that if all 3 variables are not matched within ONE line, than it will just append the parameters to the end of the file, BUT if the parameters do match then I want them to be deleted. and appended to the file. I know I can use other things like sed and awk, but I have yet to learn it, I don't mind learning how to use other commands if there's any express lessons that could be given to me for this instance before I start learning them in class.

This is for a school assignment, and all help is very much appreciated, but I'd also like to learn why and how it works/doesn't so if you can provide answers to that as well that would be great !

Not quite sure if my "if statement" used to decide between if the parameters exist or not is even that strong or good, but I am new to programming, scripting "bashing" so I welcome all constructive criticism

Thank you,
Jon
Last edited by JonLaberge; 02-17-2013 at 12:01 AM.. Reason: Forgot to mention.
 

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LEARN ABOUT LINUX

rbash

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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