[SOLVED] quick shell script question

hui · 11-18-2011, 05:44 AM

Trying to make my first shell script here, but already having problems. The first 4 lines give an error saying "1: MAP: not found" and so, although on many tutorial pages variable declaration goes just like that.

Code:

MAP = " -> ../../"
NAME_1 = "ST3250823AS_5ND145H9"MAP
NAME_2 = "2B020H1_B1LJZS9E"MAP
NAME_3 = "2B020H1_B1JDS2RE"MAP

id_1 = `ls -l /dev/disk/by-id | grep $NAME_1`
id_2 = `ls -l /dev/disk/by-id | grep $NAME_2`
id_3 = `ls -l /dev/disk/by-id | grep $NAME_3`

echo $id_1
echo $id_2
echo $id_3

approximate Java version of what I want to do:

Code:

public static final String MAP = " -> ../../";
public static final String NAME_1 = "ST3250823AS_5ND145H9" + MAP;
public static final String NAME_2 = "2B020H1_B1LJZS9E" + MAP;
public static final String NAME_3 = "2B020H1_B1JDS2RE" + MAP;

String id_1 = Linuxshell.execute("ls -l /dev/disk/by-id | grep '" + NAME_1 + "'");
String id_2 = Linuxshell.execute("ls -l /dev/disk/by-id | grep '" + NAME_2 + "'");
String id_3 = Linuxshell.execute("ls -l /dev/disk/by-id | grep '" + NAME_3 + "'");
System.out.println(id_1);
System.out.println(id_2);
System.out.println(id_3);

catkin · 11-18-2011, 06:12 AM

In bash, there is no space either side of the = operator so you need MAP=" -> ../../"

Reason is bash is an automated command shell and the "no spaces" is an easy way to avoid problems with variables having the same name as a command.

hui · 11-18-2011, 06:36 AM

Quote:

Originally Posted by catkin

In bash, there is no space either side of the = operator so you need MAP=" -> ../../"

Reason is bash is an automated command shell and the "no spaces" is an easy way to avoid problems with variables having the same name as a command.

that was totally the problem, ty.

catkin · 11-18-2011, 06:59 AM

BTW ...

To add the value of MAP to the end of the NAME_* variables, you need something like

Code:

NAME_1 = "ST3250823AS_5ND145H9"$MAP

It may help to think of $ as a dereference operator or as meaning "the value of".

Backticks for command substitution are not wrong but the later $( <command> ) form is preferred for reasons explained here.

A convention, widely but not universally used, is to reserve uppercase variable names for environment variables.

David the H. · 11-18-2011, 03:22 PM

You really shouldn't post multiple threads concerning the same basic topic. Keep related things all in one place.

I just posted two useful comments to your other thread.

http://www.linuxquestions.org/questi...g-grep-914235/