Is there a way to get hdfs location from external table and assign to unix variable.
Yes, there is a way.
Run a command like the below,
export location=hive -e "SHOW CREATE TABLE <dbname.tablname>;"| grep hdfs://
Please use after the equal sign on the above command and at the end. It is not shown here due to Stackoverflow's rich text format.
You can check the variable like the below,
echo $location
'hdfs://hostname:8020/HDFS/PATH/OF/THE/TABLE'
Hope this helps!
Related
I'm confused about this code! Why # cant't play a role that takes the length of a string?
string="abcd"
!echo ${#string}
In fact, the code behind # has become commented and cannot be executed!
Any advice?
This works correctly, but you cannot mix python and bash variables in this way. Try this instead:
!string="abcd" && echo ${#string}
The two statements have to be on the same line because in IPython, each ! statement opens a temporary subshell and variables are not persisted between shells. If you want to use multiline bash programs, you can use the %%bash cell magic instead:
%%bash
string="abcd"
echo ${#string}
trying to create a file with following data using shell script.
InsertParam.sh
echo "$$Domain=XYZ" >parameter.prm
when i run InsertParam.sh
Am getting out put as
$cat parameter.prm
1979205Domain=XYZ
Please help me how to over come this in my parameter.prm
i need Data as
$$Domain=xyz
In sh/bash/ksh/zsh, $$ is the current PID. see https://www.gnu.org/software/bash/manual/bashref.html#Special-Parameters
You need to use different quotes to prevent that variable from being expanded:
echo '$$Domain=XYZ' >parameter.prm
see https://www.gnu.org/software/bash/manual/bashref.html#Quoting
Quotes can be mixed, as required:
echo '$$Domain='"$domain" >parameter.prm
What is the right way to assign commands into variable . a.k.a how should i use quote commas and how assign it to variable , so the command is up to date? For example
i am at home/desktop
i assign variable
b=`pwd`
echo "$b" // home/desktop
but when i change the directory
cd games
pwd // home/desktop/games
echo "$b" // home/desktop
it does not update. Also i want to do something like
g="-l"
ls $g
is it possible?
Variables never update automatically, you have to re-assign them, i.e.,
b=`pwd`
echo "$b" // home/desktop
cd games
pwd // home/desktop/games
b=`pwd`
echo "$b" // home/desktop/games
as for your second question, I think that's only possible using eval:
g=" -la"
eval "ls"$g
BE VERY CAREFUL WITH THIS It's very easy to write something that can compromise security and indeed most people (including myself!) would strongly advise you never to use eval unless all else has failed.
Consider the code above for demonstration purposes only, under no circumstances to be used in a production system.
I think you are confusing assigning variables with aliases.
assigning a variable means you store the result of the command in a variable
what this command does
b=`pwd`
is running pwd and stores the answer in a variable b.
and alias means giving some command a different name. so running alias b pwd will make it so whenever you run b, you will actually run pwd
b is only set when you run the first command (assigning the output of pwd to b, it doesn't link those items together (so that b gets set on every invocation). There are ways to do that also (do man bash on your machine) (for example, the shell variable $PWD contains this information.
to your second question, yes, you can do that, but a nice way to so it is to use alias. So, alias ll='ls -l' creates a command on your system that will run ls -l when you type ll
I'm trying to automate a check for missing routes a Play! web application.
The routing table is in a file in the following format:
GET /home Home.index
GET /shop Shop.index
I've already managed to use my command line-fu to crawl through my code and make a list of all the actions that should be present in the file. This list is in the following format:
Home.index
Shop.index
Contact.index
About.index
Now I'd like to pipe the output of this text into another command that checks if each line is present in the route file. I'm not sure how to proceed though.
The result should be something like this:
Contact.index
About.index
Does someone have a helpful suggestion on how I can accomplish this?
try this line:
awk 'NR==FNR{a[$NF];next}!($0 in a)' routes.txt list.txt
EDIT
if you want the above line to accept list from stdin:
cat list.txt|awk 'NR==FNR{a[$NF];next}!($0 in a)' routes.txt -
replace cat list.txt with your magic command
I am taking a intro to Unix class and am stuck on the final assignment. I need to write a script to change the file extension of a filename that is input when the script is run. The new file extension is also input when the script is run. The script is call chExt1.sh . Our first trial of the script is run as follows
./chExt1.sh cpp aardvark.CPP
The script is suppose to change the second input file extension to the file extension given in the first input. It is not suppose to matter what file extension is given with the file name or what file extension is given as the new extension, nor is it only for changing uppercase to lowercase. In hope to make this very clear if given the following:
./chExt1.sh istink helpme.plEaSe
The script would change helpme.plEaSe to helpme.istink . I have searched on this forum and in google and have had no look with trying the different examples I found. Below is some of the examples I have tried and what I currently have.
Current
#!/bin/sh
fileExtension="$1"
shift
oldName="$2"
shift
newName=${oldName%%.*}${fileExtension}
echo $newName
The echo is just to see if it works, and if I get it working I'm going to add an mv to save it.
Others that I have tried:
newName=`${oldName%.*}`
newName=`${oldName#.*}`
sed 's/\.*//' $oldName > $newName
I can't seem to find some of the other sed I have used but they involved alot of backslashes and () with .* in there. I did not try the basename command cause I don't know the file extension to be entered and all I the examples I saw required that you specify what you wanted removed and I can't. I did not list all the different quote variations that I used but I have tried alot. My instructions say to use the sed command since we should know how to use that from class but when I try to do it I don't isolate just the ending of the file and I believe (cause it takes so long to finish) that it is going through the whole file and looking for .'s and anything after cause I kept doing .* as the pattern. Thanks for anyhelp you can give.
shift shifts the positional parameters, so after calling shift the second parameter ($2) is now the first ($1). The second shift is not necessary, because you are done accessing the parameters. You need to either remove the shift
#!/bin/sh
fileExtension="$1"
oldName="$2"
newName=${oldName%%.*}${fileExtension}
echo $newName
or change $2 to $1.
#!/bin/sh
fileExtension="$1"
shift
oldName="$1"
newName=${oldName%%.*}${fileExtension}
echo $newName
However, you are still missing a dot from your new file name. That is left as an exercise for the reader.