I'm trying to truncate a part of the file name of my present working directory. This is the code I am using:
set test = "$cwd" | awk -F "/" '{print $3}'
set USER_CUST = ${test:s/abc_//}
(Explanantion: I want to cut out the "abc_" part from the third folder from the root)
When I run the script(script_check.csh) I am getting this in my console :
tcsh -x script_check.csh
set test = /proj/proj_name/abc_username/folder/sub_folder
awk -F / {print $3}
test: Undefined variable.
Why is test an undefined variable? Is there another possible workaround?
The right-hind side of a variable declaration isn't a shell command, so you can't use pipes in there. You can see this with:
$ set test = ls
$ echo $test
ls
Why does it give the confusing "undefined variable" error? Who knows. The (t)csh parser is quirky and full of strange things like this, especially when given bad input. It's one of the main reasons scripting in (t)csh is generally discouraged (as someone pointed out in the comments) ;-)
To make it a shell command, add backticks like so:
$ set test = `echo "$cwd" | awk -F "/" '{print $3}'`
$ echo $test
martin
You can make this a bit shorter with pwd by the way:
$ set test = `pwd | awk -F "/" '{print $2}'`
Related
Attempting to get the last word of the first line from a file. Not sure why the following command:
send "cat moo.txt | grep QUACK * | awk 'NF>1{print $NF}' meow.txt >> bark.txt "
is getting the error message can't read "NF": no such variable.
I can run the awk 'NF>1{print $NF}' meow.txt >> bark.txt snippet just fine on my machine. Yet, when it runs in my expect script, it gives me that error.
Anyone know why expect doesn't recognize the awk built-in variable?
I think your script is trying to expand the variable $NF with it's value before shooting that command through send. $NF isn't set in your shell since it's internal to awk, which hasn't had a chance to even run yet and so it's balking.
Try escaping that variable so it is treated as a string literal and awk will be able to use it when it comes time for awk to run:
send "cat moo.txt | grep QUACK * | awk 'NF>1{print \$NF}' meow.txt >> bark.txt "
Why doesn't this work?
x=5
$ ls -l | awk '{print $(($x))}'
should print field 5 of ls -l command, right?
The only ways you should pass in the value of shell variable to awk are the following
$ x=5
$ ls -l | awk -v x="$x" '{print $x}'
$ ls -l | awk '{print $x}' x="$x"
The main difference between these two methods is that by using -v the value of x is set in the BEGIN block whilst the second method the value would not be set. All other methods with quoting tricks or escaping should not be used unless you like headaches.
However you don't want to being parsing ls at all, the command you really want is:
stat --printf="%s\n" *
Assuming the fifth column of your ls is the same as mine, this will display all the file sizes in the current directory.
You could access the shell variable something similar to these;
The first way is not suggested!
x=5
ls -l | awk '{print $'$x'}'
or assigning the value x to the variable shellVar, before execution of the program begins
x=5
ls -l | awk -v shellVar="$x" '{print $shellVar}'
or using an array containing the values of the current environment
export x=5
ls -l | awk '{print $ENVIRON["x"]}'
That's a shell variable, which is not expanded by the shell in single quotes. The reason we put awk scripts in single quotes is precisely to prevent the shell from interpreting things meant for awk's benefit and screwing things up, but sometimes you want the shell to interpret part of it.
For something like this, I prefer to pass the value in as an awk variable:
ls -l | awk -v "x=$x" '{print $x}'
but you could do any number of other ways. For instance, this:
ls -l | awk '{print $'$x'}'
which should really be this:
ls -l | awk '{print $'"$x"'}'
alternatively, this:
ls -l | awk "{print \$$x}"
Try this :
ls -l | awk '{print $'$x'}'
Can we use shell variables in AWK like $VAR instead of $1, $2? For example:
UL=(AKHIL:AKHIL_NEW,SWATHI:SWATHI_NEW)
NUSR=`echo ${UL[*]}|awk -F, '{print NF}'`
echo $NUSR
echo ${UL[*]}|awk -F, '{print $NUSR}'
Actually am an oracle DBA we get lot of import requests. I'm trying to automate it using the script. The script will find out the users in the dump and prompt for the users to which dump needs to be loaded.
Suppose the dumps has two users AKHIL, SWATHI (there can be may users in the dump and i want to import more number of users). I want to import the dumps to new users AKHIL_NEW and SWATHI_NEW. So the input to be read some think like AKHIL:AKHIL_NEW,SWATHI:SWATHI_NEW.
First, I need to find the Number of users to be created, then I need to get new users i.e. AKHIL_NEW,SWATHI_NEW from the input we have given. So that I can connect to the database and create the new users and then import. I'm not copying the entire code: I just copied the code from where it accepts the input users.
UL=(AKHIL:AKHIL_NEW,SWATHI:SWATHI_NEW) ## it can be many users like USER1:USER1_NEW,USER2_USER2_NEW,USER3:USER_NEW..
NUSR=`echo ${UL[*]}|awk -F, '{print NF}'` #finding number of fields or users
y=1
while [ $y -le $NUSR ] ; do
USER=`echo ${UL[*]}|awk -F, -v NUSR=$y '{print $NUSR}' |awk -F: '{print $2}'` #getting Users to created AKHIL_NEW and SWATHI_NEW and passing to SQLPLUS
if [[ $USER = SCPO* ]]; then
TBS=SCPODATA
else
if [[ $USER = WWF* ]]; then
TBS=WWFDATA
else
if [[ $USER = STSC* ]]; then
TBS=SCPODATA
else
if [[ $USER = CSM* ]]; then
TBS=CSMDATA
else
if [[ $USER = TMM* ]]; then
TBS=TMDATA
else
if [[ $USER = IGP* ]]; then
TBS=IGPDATA
fi
fi
fi
fi
fi
fi
sqlplus -s '/ as sysdba' <<EOF # CREATING the USERS in the database
CREATE USER $USER IDENTIFIED BY $USER DEFAULT TABLESPACE $TBS TEMPORARY TABLESPACE TEMP QUOTA 0K on SYSTEM QUOTA UNLIMITED ON $TBS;
GRANT
CONNECT,
CREATE TABLE,
CREATE VIEW,
CREATE SYNONYM,
CREATE SEQUENCE,
CREATE DATABASE LINK,
RESOURCE,
SELECT_CATALOG_ROLE
to $USER;
EOF
y=`expr $y + 1`
done
impdp sysem/manager DIRECTORY=DATA_PUMP DUMPFILE=imp.dp logfile=impdp.log SCHEMAS=AKHIL,SWATHI REMPA_SCHEMA=${UL[*]}
In the last impdp command I need to get the original users in the dumps i.e AKHIL,SWATHI using the variables.
Yes, you can use the shell variables inside awk. There are a bunch of ways of doing it, but my favorite is to define a variable with the -v flag:
$ echo | awk -v my_var=4 '{print "My var is " my_var}'
My var is 4
Just pass the environment variable as a parameter to the -v flag. For example, if you have this variable:
$ VAR=3
$ echo $VAR
3
Use it this way:
$ echo | awk -v env_var="$VAR" '{print "The value of VAR is " env_var}'
The value of VAR is 3
Of course, you can give the same name, but the $ will not be necessary:
$ echo | awk -v VAR="$VAR" '{print "The value of VAR is " VAR}'
The value of VAR is 3
A note about the $ in awk: unlike bash, Perl, PHP etc., it is not part of the variable's name but instead an operator.
Awk and Gawk provide the ENVIRON associative array that holds all exported environment variables. So in your awk script you can use ENVIRON["VarName"] to get the value of VarName, provided that VarName has been exported before running awk.
Note ENVIRON is a predefined awk variable NOT a shell environment variable.
Since I don't have enough reputation to comment on the other answers I have to include them here!
The earlier answer showing $ENVIRON is incorrect - that syntax would be expanded by the shell, and probably result in expanding to nothing.
Further earlier comments about C not being able to access environment variable is wrong. Contrary to what is said above, C (and C++) can access environment variables using the getenv("VarName") function. Many other languages provide similar access (e.g., Java: System.getenv(), Python: os.environ, Haskell System.Environment, ...). Note in all cases access to environment variables is read-only, you cannot change an environment variable in a program and get that value back to the calling script.
There are two ways to pass variables to awk: one way is defining the variable in a command line argument:
$ echo ${UL[*]}|awk -F, -v NUSR=$NUSR '{print $NUSR}'
SWATHI:SWATHI_NEW
Another way is converting the shell variable to an environment variable using export, and reading the environment variable from the ENVIRON array:
$ export NUSR
$ echo ${UL[*]}|awk -F, '{print $ENVIRON["NUSR"]}'
SWATHI:SWATHI_NEW
Update 2016: The OP has comma-separated data and wants to extract an item given its index. The index is in the shell variable NUSR. The value of NUSR is passed to awk, and awk's dollar operator extracts the item.
Note that it would be simpler to declare UL as an array of more than one element, and do the extraction in bash, and take awk out of the equation completely. This however uses 0-based indexing.
UL=(AKHIL:AKHIL_NEW SWATHI:SWATHI_NEW)
NUSR=1
echo ${UL[NUSR]} # prints SWATHI:SWATHI_NEW
There is another way, but it could cause immense confusion:
$ VarName="howdy" ; echo | awk '{print "Just saying '$VarName'"}'
Just saying howdy
$
So you are temporarily exiting the single quote environment (which would normally prevent the shell from interpreting '$') to interpret the variable and then going back into it. It has the virtue of being relatively brief.
Not sure if i understand your question.
But lets say we got a variable number=3 and we want to use it istead of $3, in awk we can do that with the following code
results="100 Mbits/sec 110 Mbits/sec 90 Mbits/sec"
number=3
speed=$(echo $results | awk '{print '"\$${number}"'}')
so the speed variable will get the value 110.
Hope this helps.
No. You can pass the value of a shell variable to an awk script just like you can pass the value of a shell variable to a C program but you cannot access a shell variable in an awk script any more than you could access a shell variable in a C program. Like C, awk is not shell. See question 24 in the comp.unix.shell FAQ at cfajohnson.com/shell/cus-faq-2.html#Q24.
One way to write your code would be:
UL="AKHIL:AKHIL_NEW,SWATHI:SWATHI_NEW"
NUSR=$(awk -F, -v ul="$UL" 'BEGIN{print gsub(FS,""); exit}')
echo "$NUSR"
echo "$UL" | awk -F, -v nusr="$NUSR" '{print $nusr}' # could have just done print $NF
but since your original starting point:
UL=(AKHIL:AKHIL_NEW,SWATHI:SWATHI_NEW)
was declaring UL as an array with just one entry, you might want to rethink whatever it is you're trying to do as you may have completely the wrong approach.
awk -F, -f awkfile.awk -v mysearch="search term"
I am trying to use the above command from terminal and use search as the search term in the awk program. My awk program runs perfectly fine while actually assigning the search term inside of the program but I am wondering how to get the variable search to be used?
example of the line it's used at if($j ~ /mysearch/){, this does not work at setting the search term, but actually searching for the string mysearch.
Just remove the slashes:
$j ~ mysearch
This is not ideal, but I suggest to write a bash script, which takes in the search term, replace that search term in the awk script, then run the script. For example:
$ cat dosearch.sh
sed "s/XXX/$1/" awktemplate.awk > awkfile.awk
awk -f awkfile.awk data.txt
$ cat awktemplate.awk
{
j = 1
if ($j ~ /XXX/) {
# Do something, such as
print "Found:", $0
}
}
$ cat data.txt
foo here
bar there
xyz everywhere
$ ./dosearch.sh foo
Found: foo here
$ ./dosearch.sh bar
Found: bar there
In the above example, the awk template contains "XXX" as a search term, the bash script replaces that search term with the first parameter, then invoke awk on the modified script.
$ cat input
tinky-winky
dipsy
laa-laa
noo-noo
po
$ teletubby='po'
$ awk -v "regexp=$teletubby" '$0 ~ regexp' input
po
Note that anything could go into the shell-variable,
even a full-blown regexp, e.g ^d.*y. Just make sure to use single-quotes
to prevent the shell from doing any expansion.
I am using the below code to change an existing awk script so that I can add more and more cases with a simple command.
echo `awk '{if(/#append1/){print "pref'"$1"'=0\n" $0 "\n"} else{print $0 "\n"}}' tf.a
note that the first print is "pref'"$1"'=0\n" so it is referring to the variable $1 in its environment, not in awk itself.
The command ./tfb.a "c" should change the code from:
BEGIN{
#append1
}
...
to:
BEGIN{
prefc=0
#append1
}
...
However, it gives me everything on one line.
Does anyone know why this is?
If you take awk right out of the equation you can see what's going on:
# Use a small test file instead of an awk script
$ cat xxx
hello
there
$ echo `cat xxx`
hello there
$ echo "`cat xxx`"
hello
there
$ echo "$(cat xxx)"
hello
there
$
The backtick operator expands the output into shell "words" too soon. You could play around with the $IFS variable in the shell (yikes), or you could just use double-quotes.
If you're running a modern sh (e.g. ksh or bash, not the "classic" Bourne sh), you may also want to use the $() syntax (it's easier to find the matching start/end delimiter).
do it like this. pass the variable from shell to awk properly using -v
#!/bin/bash
toinsert="$1"
awk -v toinsert=$toinsert '
/#append1/{
$0="pref"toinsert"=0\n"$0
}
{print}
' file > temp
mv temp file
output
$ cat file
BEGIN{
#append1
}
$ ./shell.sh c
BEGIN{
prefc=0
#append1
}