I believe data_dir to be a more conventional link to a directory.
No. In fact it is a "variable". Suppose the following: i don't know where you installed a certain program, but i know how the place where the program is installed looks like because i work with it a lot. So, if you ask me where you can find the logs of the program, i'd tell you: "go to where you installed the program". In there, whereever that is, you find a directory "<somewhere>/logs" and inside of this you find a directory "<somewhere>/log/program-logs", ... Now, you might ask me something else about this program and again, i'd refer to the (to me unknown) location of the program as "<somewhere>" and direct you to some plcae relative to there.
This is what variables are for: you define them by assigning some value (in your case the value /usr/local/entity/project) to a name (data_dir) and then you can use it everywhere without needing to know the exact value of it. Just like i used the name "<somewhere>" above. I could have used a variable:
and in this case the logs would have been there:
The second and third lines use the variable we have defined before: $program_location is first replaced by what we assigned to the name "program_location" before, only then "/logs" or respectively "/logs/program-logs" is appended. So the real commands read:
Quote:
Originally Posted by Circuits
However, I am not sure what PATH is. It also seems like a location but maybe it's multiple possible locations? Does the : signify that the location could be either: /usr/bin, /bin, /usr/sbin or /usr/local/entity/bin? Is the : in this context similar to some function like [ is to the test function?
PATH is a special kind of variable. Or, rather, a normal variables (everything i said above applies) but with a special function. You see, a program is a certain file (where executable code is stored). To execute the program you have to write the full name of the program file:
As the pathes get longer this might be a lot of work to type. Computer people are in general of the lazy sort (this is why we use computers to do it for us). Since many programs are collected in a few directories (i.e. most of the systems commands are stored in /usr/bin) the PATH variable was invented. It holds a list of directories, separated by ":". The rule is: if a program is located in one of the directories in this list then you do not need to specify the path when calling it.
That means: your path looks like this:
This is a list of directories: /usr/bin, /bin, /usr/sbin, /sbin and /usr/local/entity/bin. For instance there is a command cp (it copies files) located in /usr/bin. So, to call it and copy the file "file" to a new file called "new_file" you would have to use the command
But since /usr/bin is included in your PATH variable you can omit that and write:
I am trying to create an alias for a frequently used directory path by using
alias xyz="/proj/dir_name"
and then trying to reach a sub-directoy by using
cd xyz/abc
but I get an error saying " No such file or directory "
plz tell me wats wrong with this ... (3 Replies)
I cannot seem to get the following script to work. I cannot seem to set the variable. What am I missing?
bin/bash
set -x
echo "2" > /tmp/number
STATUS='grep -c 2 /temp/number'
if ; then
echo "Number 2 is found once"
else
echo "Number 2 is found more or less than one time"
fi (3 Replies)
Hi,
I am having a variable
Like
line="/dir1/dir2/gr3/file.ksh"
I need to get the /dir1/dir2/gr3 alone. the no of directories may differ at each time.
Please advice. thanks in advance. (3 Replies)
Hello,
i have another sed question.. I'm trying to do variable substition with sed and i'm running into a problem.
my var1 is a string constructed like this:
filename1 filerev1 filepath1
my var2 is another string constructed like this:
filename2 filerev2 filepath2
when i do... (2 Replies)
Hi
I need a script which will remove a path from PATH environment variable. For example
$echo PATH
/usr/local/bin:/usr/bin:test/rmve:/usr/games
$echo rmv
test/rmve
Here I need a shell script which will remove rmv path (test/rmve) from PATH... (9 Replies)
Hi,
Could anyone help me in writing a single line code by either using (sed, awk, perl or whatever) to extract a specific path from the PATH environment variable?
for eg: suppose the PATH is being set as follows
PATH=/usr/bin/:/usr/local/bin:/bin:/usr/sbin:/usr/bin/java:/usr/bin/perl3.4
... (2 Replies)
Hello Folks,
I want to append a path in user's PATH variable which should be available in current session.
Background
Numerous persons will run a utility.
Aim is to add the absolute path of the utility the first time it runs so that next runs have the PATH in env & users can directly run... (6 Replies)
Hi I'm trying to select text between two lines, I'm using sed to to this, but I need to pass variables to it. For example
start="BEGIN /home/mavkoup/data"
end="END"
sed -n -e '/${start}/,/${end}/g' doesn't work. I've tried double quotes as well. I think there's a problem with the / in the... (4 Replies)
I am submitting a concurrent program (of HOST tyme) from Oracle apps screen,
The MAIN shell program submits another program, (child) which is also a Shell program. The child writes data to log file. Now the main program, read the log and do some calculations and sends the data to user through... (1 Reply)
Need a way to read a file in who every line is a path to a directory and make shortcut to that directory on a specific place.
Example:
line in the document
/media/gogo/6651-FEAB/Desktop/
/media/gogo/6651-FEAB/Desktop/alex/
/media/gogo/6651-FEAB/linux/ ... (3 Replies)