10 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
Greetings!
I need a quick way to change the format in a table of data
Here is an example of the input:
10 72 Value=177 VDB=0.0245 Value4=0,0,171,0
10 274 Value=238 VDB=0.0433 Value4=29,0,205,0
10 312 Value=222 VDB=0.0384 Value4=8,0,190,19
10 540 Value=405 VDB=0.0391 Value4=13,30,153,195... (3 Replies)
Discussion started by: Twinklefingers
3 Replies
2. UNIX for Dummies Questions & Answers
Hello
Im new treat me nicely, I have a headache :)
I have a script that seemed to work now it doesnt anyway, the last part is adding counts of unique items in a csv file eg
05492U34 38
05492U34 47
two columns, (many different values like this in file)
i want... (7 Replies)
Discussion started by: aniquebmx
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3. Shell Programming and Scripting
Hi everyone!
I sometimes need to do some simple arithmetics, like adding a number to a certain column of a file. So I wrote a small function in the .bashrc file, which looks like this
shifter()
{
COL=$1
VAL=$2
FILE=$3
cp $FILE $FILE.shifted
awk 'NF==4 {$(( $COL )) = $(( $COL ))... (6 Replies)
Discussion started by: radudownload
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4. Shell Programming and Scripting
Hello all,
I need to add a coloumn at the 5th Position of a file, Can this be done using awk or sed.
Sample Input
1008,300186,R,2009,0,2,2,3,2,0,1,1,1,1,2,1,1,0,2,1,1,0,2,2,2,2,0,0,0,0,1,0,2,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,,0,0,0,0,0,0,0,0,3,2,3,1,1,1,
Ouput:
... (4 Replies)
Discussion started by: Sri3001
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5. Linux
Hello,
I am a newbie to linux and struggling to find a better way to append a column in a text file.
Here is the file i want to modify: It has 8 columns (and thousands of rows). I want to append the first column by adding "chr" infront of the numbers. Some rows have a string in the first... (4 Replies)
Discussion started by: bjorngill
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6. Shell Programming and Scripting
Hello everyone,
I have a file with the following structure:
abc xyz 111 222
agf hjhf 787 799
tht yah 878 898
... ... ... ...
... ... ... ...
... ... ... ...
I want to add a column (with a fixed value of 1000) at the end such that it becomes:
abc xyz 111 222 1000
agf hjhf 787... (5 Replies)
Discussion started by: ad23
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7. UNIX for Dummies Questions & Answers
Is there anyway to use awk to add a first column to my data that automatically goes from 1 to n , where n is the numbers of my rows?:confused: (4 Replies)
Discussion started by: cosmologist
4 Replies
8. Shell Programming and Scripting
I have a txt file as follows
Code:
Oct 1 file1 4144
Oct 1 file23 5170
Oct 2 file5 3434
Oct 21 file56 2343
I need to add a new column by marking the right log file from current directory. For example populate like this. Please not in the second columt for "1" it has... (2 Replies)
Discussion started by: gubbu
2 Replies
9. Shell Programming and Scripting
Hi,
I have a file "input.txt" with the following content :
5312,0,,,1,8,141.2,20090727
3714,0,,,1,8,285.87,20090727
5426,0,,,1,8,3.9,20090727
3871,0,,,1,8,30.4,20090727
9071,0,,,1,8,146.2,20090727
5141,0,,,1,8,2.8,20090727
0460,0,,,1,8,-0.1,20090727
7918,0,,,1,8,-0.1,20090727... (3 Replies)
Discussion started by: valokv
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10. Shell Programming and Scripting
Is it possible to add a new column in a file by matching a key element in second file ?
File 1
2 a
3 b
4 d
5 g
6 j
7 m
File 2
4 hjjjj
5 aaa
6 sasa
7 dsds
2 dsdf
3 fdsfg (2 Replies)
Discussion started by: sandeep_hi
2 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 v5.12.4 2011-06-01 A2P(1)