ok , so sed/awk have not worked in here as
tr output : alpha,beta,gamma, did not contain a new line in them. And this behaviour is also sed/awk version specific.
now with awk we can change the record seperator right ? so should not something like this work logically ?
since my tr output does not have a newline i am using RS=""
You can use RS to change the record separator, but that does not alter the fact that the behavior of sed and awk is only defined when the input file is a text file. If there are any characters at the end of a file without a trailing <newline> character, the input is not a text file.
If the input is not a text file, the behavior is unspecified.
Will the unspecified behavior change if the value of RS changes; the answer to that is unspecified. It might work; it might not; it might vary depending on which awk or sed you use.
I agree with what you say and I know for a fact that some sed's do process that last line, other's don't so as you say the results are unspecified. However, I have never come across a version of awk that does not process that last unterminated line, and I am wondering why that might be. Even oawk on Solaris will process it:
Could it perhaps be that awk is almost 'obliged' to process that last line anyway because of the concept of RS, the input record separator which can be set to almost any character. So what might be a consequence of this is that any characters that follow that last RS, should be interpreted as being part of the last record? Otherwise it should have been called RT (Record Terminator)?
Another example would be that if the were not the case then from a UNIX point of view what this printf produces is a valid UNIX text file, but from an awk point of view - if you compare that to the situation where RS is a regular newline - this would be an "unterminated" last record
I agree with what you say and I know for a fact that some sed's do process that last line, other's don't so as you say the results are unspecified. However, I have never come across a version of awk that does not process that last unterminated line, and I am wondering why that might be. Even oawk on Solaris will process it:
Could it perhaps be that awk is almost 'obliged' to process that last line anyway because of the concept of RS, the input record separator which can be set to almost any character. So what might be a consequence of this is that any characters that follow that last RS, should be interpreted as being part of the last record? Otherwise it should have been called RT (Record Terminator)?
Another example would be that if the were not the case then from a UNIX point of view what this printf produces is a valid UNIX text file, but from an awk point of view - if you compare that to the situation where RS is a regular newline - this would be an "unterminated" last record
After all that last newline is not a file terminator, but a line terminator..
Yes, the last newline is a line terminator. So the input file consists of lines. And, each line is no more than LINE_MAX bytes (including the terminating newline) and there are no null bytes in any line. Therefore, by definition, the input is a text file.
The behavior of awk and sed is defined when the input is a text file no matter what the record separator is.
If the input file had been created by printf "hello,hello" (note that there is no trailing newline), the results would be unspecified no matter how RS is set because the input fiile would not be a text file.
Whenever the below command is being executed by a scheduler at UNIX environment, we are getting below error
cd /tmp/log
find . -ignore_readdir_race ! -name . -prune -iname 'XYZ*' -type f -mtime +4 -printf "%f\n"
./tmpfile.script_name.2.31885.201906071336.tmp': No such file or directory... (2 Replies)
Basically I was wondering if any of you know how to pipe the output of ls to a text file? so in my shell script one of the lines is ls but i want to pipe it into a file called directory listing.
Cheers.
I have tried ls | Directorylisting.txt
but it keeps saying " line 7: DirectoryListing.txt:... (9 Replies)
Ok, so there is a perl script that runs as a server, on my local host. It tells me which port to use. I want to pipe that output into my browser so I can do the whole thing with a single command. The problem is, I think, that the program doesn't actually exit cause it's running a server, so...... (6 Replies)
Hi all. I am using procmail to deliver an email to a script I am developing. Procmail delivers the email to the script on standard input. I imagine this is the same as piping input from a command into the script. Hence I've been testing my script by running
echo 'test' | sms-autosend-backup.sh
... (2 Replies)
Hi All,
I am trying to convert the below Csh code into Perl.
But i have the following error.
Can any expert help ?
Error:
ls: *tac: No such file or directory
Csh
set $ST_file = `ls -rt *$testid*st*|tail -1`;
Perl
my $ST_file = `ls -rt *$testid*st*|tail -1`; (10 Replies)
Hi All...
Does anyone know how to pipe the output of a "select" statement from a call to Oracle to a file?
ANy ideas woule be greatly appreciated!
Code is as below...
echo "producing CSV file 2..."
sqlplus -s $username/$password@$database<<EOF
set serveroutput on size 1000000
set... (13 Replies)
Not sure why this does not work in bash:
tail -f err.log |&
-bash: syntax error near unexpected token `&'
I am attempting to continuously read a file that is being updated by doing a "tail -f" on the file and piping the output to stdin which can then be read by the next shell command
Thnx (4 Replies)
Hi,
I was wondering why ls * | echo does not print the contents of the directory to the screen? The way I see it, ls * returns a whole lot of information, and then we pipe all this info to echo, so surely it should all come to our screen!
Is there a serious flaw in my understanding?
... (3 Replies)
Hi,
I did not understand why the following did not work out as I expected:
find . -name "pqp.txt" | grep -v "Permission"
I thought I would be able to catch whichever paths containing my pqp.txt file without receiving the display of messages such as "find: cannot access... Permisson... (1 Reply)
Hi. Im using cat to output the contents of a file, then piping it to my while read loop.In this loop variables get assigned values. However when i try to use the variables outside the loop their values has been reset.I understand about subshells etc. but I have no idea how to "preserve" the... (3 Replies)
