10 More Discussions You Might Find Interesting
1. UNIX for Beginners Questions & Answers
I have the following script, and I want to assign the output ($10 and $5) from awk to N and L:
grdinfo data.grd | awk '{print $10,$5}'| read N L
output from gridinfo data.grd is: data.grd 50 100 41 82 -2796 6944 0.016 0.016 3001 2461. where N and L is suppose to be 3001 and 100. I use... (8 Replies)
Discussion started by: geomarine
8 Replies
2. Shell Programming and Scripting
Hi people,
I would like to start a review of my config variable to check whether they have been changed and if not then there is only an echo. If they have been changed to my other commands are executed.
I hope you can help me.
with best regards
JPad
edit:
here my code
if ;... (8 Replies)
Discussion started by: JPad
8 Replies
3. Shell Programming and Scripting
I have a script /root/asas with following contents.
#!/bin/bash
ha=`cat /etc/passwd | grep sandra`
if ; then
echo "Sandra is in /etc/passwd"
echo "variable ha is $ha"
else
echo "Sandra is NOT in /etc/passwd"
echo "variable ha is $ha"
fi
What... (3 Replies)
Discussion started by: anil510
3 Replies
4. Shell Programming and Scripting
Hello experts,
I'm stuck with this script for three days now. Here's what i need.
I need to split a large delimited (,) file into 2 files based on the value present in the last field.
Samp: Something.csv
bca,adc,asdf,123,12C
bca,adc,asdf,123,13C
def,adc,asdf,123,12A
I need this split... (6 Replies)
Discussion started by: shell_boy23
6 Replies
5. Shell Programming and Scripting
#!/bin/sh
echo "Running Script to capture ORACLE Erros"
# Change Directory to the actual logs path
cd /home/nv8510/lognew
err_var=`grep -in "ORA-" *`
if then
echo "THESE ARE THE ORACLE ERROR OCCURED"
echo "$err_var"
echo... (7 Replies)
Discussion started by: neeraj617
7 Replies
6. Shell Programming and Scripting
Hi all,
Hope someone can help me out here.
I have this BASH script (see below)
My problem lies with the variable path.
The output of the command find will give me several fields. The 9th field is the path. I want to captured that and the I want to filter this to a specific level.
The... (6 Replies)
Discussion started by: Cowardly
6 Replies
7. Shell Programming and Scripting
I have seen many posts for this sort of problem but I just did not know how to use it for my issue. A number is assigned to a variable and I wanted to check if it is a zero or non zero.
Example of my numbers are below:
000000000000000000000000000000000000000000000000... (8 Replies)
Discussion started by: soujiv
8 Replies
8. Shell Programming and Scripting
Dear All,
we have a command output which looks like :
Total 200 queues in 30000 Kbytes
and we're going to get "200" and "30000" for further process. currently, i'm using :
numA=echo $OUTPUT | awk '{print $2}'
numB=echo $OUTPUT | awk '{print $5}'
my question is : can I use just one... (4 Replies)
Discussion started by: tiger2000
4 Replies
9. Shell Programming and Scripting
Hi,
I want to check if a variable has a value assigned to it or not.
I can do following -
cat $Var > File1
if
then
echo "$Var has value"
else
echo "$Var is null"
fi
But I have to check for 3 Variables and I want to wrap it up in couple of unix statements.
Any... (3 Replies)
Discussion started by: sumeet
3 Replies
10. Shell Programming and Scripting
Hi
I am writing a bash script and would like to check is a variable contains a . or not
ex.
a=102 output ok
a=1.02 output not ok
Many thanks, (3 Replies)
Discussion started by: gekkos
3 Replies
A2P(1) Perl Programmers Reference Guide A2P(1)
NAME
a2p - Awk to Perl translator
SYNOPSIS
a2p [options] [filename]
DESCRIPTION
A2p takes an awk script specified on the command line (or from standard input) and produces a comparable perl script on the standard
output.
OPTIONS
Options include:
-D<number>
sets debugging flags.
-F<character>
tells a2p that this awk script is always invoked with this -F switch.
-n<fieldlist>
specifies the names of the input fields if input does not have to be split into an array. If you were translating an awk script that
processes the password file, you might say:
a2p -7 -nlogin.password.uid.gid.gcos.shell.home
Any delimiter can be used to separate the field names.
-<number>
causes a2p to assume that input will always have that many fields.
-o tells a2p to use old awk behavior. The only current differences are:
o Old awk always has a line loop, even if there are no line actions, whereas new awk does not.
o In old awk, sprintf is extremely greedy about its arguments. For example, given the statement
print sprintf(some_args), extra_args;
old awk considers extra_args to be arguments to "sprintf"; new awk considers them arguments to "print".
"Considerations"
A2p cannot do as good a job translating as a human would, but it usually does pretty well. There are some areas where you may want to
examine the perl script produced and tweak it some. Here are some of them, in no particular order.
There is an awk idiom of putting int() around a string expression to force numeric interpretation, even though the argument is always
integer anyway. This is generally unneeded in perl, but a2p can't tell if the argument is always going to be integer, so it leaves it in.
You may wish to remove it.
Perl differentiates numeric comparison from string comparison. Awk has one operator for both that decides at run time which comparison to
do. A2p does not try to do a complete job of awk emulation at this point. Instead it guesses which one you want. It's almost always
right, but it can be spoofed. All such guesses are marked with the comment ""#???"". You should go through and check them. You might
want to run at least once with the -w switch to perl, which will warn you if you use == where you should have used eq.
Perl does not attempt to emulate the behavior of awk in which nonexistent array elements spring into existence simply by being referenced.
If somehow you are relying on this mechanism to create null entries for a subsequent for...in, they won't be there in perl.
If a2p makes a split line that assigns to a list of variables that looks like (Fld1, Fld2, Fld3...) you may want to rerun a2p using the -n
option mentioned above. This will let you name the fields throughout the script. If it splits to an array instead, the script is probably
referring to the number of fields somewhere.
The exit statement in awk doesn't necessarily exit; it goes to the END block if there is one. Awk scripts that do contortions within the
END block to bypass the block under such circumstances can be simplified by removing the conditional in the END block and just exiting
directly from the perl script.
Perl has two kinds of array, numerically-indexed and associative. Perl associative arrays are called "hashes". Awk arrays are usually
translated to hashes, but if you happen to know that the index is always going to be numeric you could change the {...} to [...].
Iteration over a hash is done using the keys() function, but iteration over an array is NOT. You might need to modify any loop that
iterates over such an array.
Awk starts by assuming OFMT has the value %.6g. Perl starts by assuming its equivalent, $#, to have the value %.20g. You'll want to set
$# explicitly if you use the default value of OFMT.
Near the top of the line loop will be the split operation that is implicit in the awk script. There are times when you can move this down
past some conditionals that test the entire record so that the split is not done as often.
For aesthetic reasons you may wish to change index variables from being 1-based (awk style) to 0-based (Perl style). Be sure to change all
operations the variable is involved in to match.
Cute comments that say "# Here is a workaround because awk is dumb" are passed through unmodified.
Awk scripts are often embedded in a shell script that pipes stuff into and out of awk. Often the shell script wrapper can be incorporated
into the perl script, since perl can start up pipes into and out of itself, and can do other things that awk can't do by itself.
Scripts that refer to the special variables RSTART and RLENGTH can often be simplified by referring to the variables $`, $& and $', as long
as they are within the scope of the pattern match that sets them.
The produced perl script may have subroutines defined to deal with awk's semantics regarding getline and print. Since a2p usually picks
correctness over efficiency. it is almost always possible to rewrite such code to be more efficient by discarding the semantic sugar.
For efficiency, you may wish to remove the keyword from any return statement that is the last statement executed in a subroutine. A2p
catches the most common case, but doesn't analyze embedded blocks for subtler cases.
ARGV[0] translates to $ARGV0, but ARGV[n] translates to $ARGV[$n-1]. A loop that tries to iterate over ARGV[0] won't find it.
ENVIRONMENT
A2p uses no environment variables.
AUTHOR
Larry Wall <larry@wall.org>
FILES
SEE ALSO
perl The perl compiler/interpreter
s2p sed to perl translator
DIAGNOSTICS
BUGS
It would be possible to emulate awk's behavior in selecting string versus numeric operations at run time by inspection of the operands, but
it would be gross and inefficient. Besides, a2p almost always guesses right.
Storage for the awk syntax tree is currently static, and can run out.
perl v5.12.1 2010-04-26 A2P(1)