I have a line
echo "object smtp aaa smtp.asd.com server.smtp.com eq smtp"
object smtp aaa smtp.asd.com server.smtp.com eq smtp
and I need to replace the smtp with 25 but just were the smtp is standing alone. The expected output should be
object 25 aaa smtp.asd.com server.smtp.com eq 25
It is not possible to use the \b or < > boundaries because there is a comma. I've tried to use
echo "object smtp aaa smtp.asd.com server.smtp.com eq 25" | sed -E 's/smtp[^.]?$/25/g'
object smtp aaa smtp.asd.com server.smtp.com eq 25
but it replaces just match at the end of the line. The
echo "object smtp aaa smtp.asd.com server.smtp.com eq smtp" | sed -E 's/smtp[^.]?( |$)/25/g'
object 25aaa smtp.asd.com server.smtp.com eq 25
replaces also the space. Does somebody has an idea how to solve the problem?
You may use this sed:
s="object smtp aaa smtp.asd.com server.smtp.com eq smtp"
sed -E -e ':a' -e 's/(^|[[:blank:]])smtp([[:blank:]]|$)/\125\2/g;ta' <<< "$s"
object 25 aaa smtp.asd.com server.smtp.com eq 25
Here:
:a: Sets label a
s/(^|[[:blank:]])smtp([[:blank:]]|$)/\125\2/g replaces each smtp with 25 if it preceded by start position or whitespace and if it is followed by whitespace or end position
ta: Goes back to label a if substitution is successful
Online Demo
With a GNU sed, if you need to match smpt as a whole word that has no dot at the end, you can use
s="object smtp aaa smtp.asd.com server.smtp.com eq smtp"
sed -E 's/\bsmtp([^.]|$)/25\1/g' <<< "$s"
See the online demo. Details:
\b - a word boundary
smtp - smtp substring
([^.]|$) - Capturing group 1 (\1 refers to this value in the replacement): any char other than a . char ([^.]), or (|) the end of string ($).
The same can be done with perl:
s="object smtp aaa smtp.asd.com server.smtp.com eq smtp"
perl -pe 's/\bsmtp\b(?!\.)/25/g' <<< "$s"
See this online demo.
Here, \bsmtp\b(?!\.) matches a whole word smtp (with \bsmtp\b) that is not immediately followed with a . char ((?!\.)).
Another solution with perl is to match smtp within whitespace boundaries:
perl -pe 's/(?<!\S)smtp(?!\S)/25/g' <<< "$s"
See this demo. However, in this case, it won't replace smtp in smtp-server since smtp in this case should be inside whitespaces or start/end of string.
Related
First, this is not a duplicate of, e.g., How can I replace each newline (\n) with a space using sed?
What I want is to exactly replace every newline (\n) in a string, like so:
printf '%s' $'' | sed '...; s/\n/\\&/g'
should result in the empty string
printf '%s' $'a' | sed '...; s/\n/\\&/g'
should result in a (not followed by a newline)
printf '%s' $'a\n' | sed '...; s/\n/\\&/g'
should result in
a\
(the trailing \n of the final line should be replaced, too)
A solution like :a;N;$!ba; s/\n/\\&/g from the other question doesn't do that properly:
printf '%s' $'' | sed ':a;N;$!ba; s/\n/\\&/g' | hd
works;
printf '%s' $'a' | sed ':a;N;$!ba;s/\n/\\&/g' | hd
00000000 61 |a|
00000001
works;
printf '%s' $'a\nb' | sed ':a;N;$!ba;s/\n/\\&/g' | hd
00000000 61 5c 0a 62 |a\.b|
00000004
works;
but when there's a trailing \n on the last line
printf '%s' $'a\nb\n' | sed ':a;N;$!ba;s/\n/\\&/g' | hd
00000000 61 5c 0a 62 0a |a\.b.|
00000005
it doesn't get quoted.
Easier to use perl than sed, since it has (by default, at least) a more straightforward treatment of the newlines in its input:
printf '%s' '' | perl -pe 's/\n/\\\n/' # Empty string
printf '%s' a | perl -pe 's/\n/\\\n/' # a
printf '%s\n' a | perl -pe 's/\n/\\\n/' # a\<newline>
printf '%s\n' a b | perl -pe 's/\n/\\\n/' # a\<newline>b\<newline>
# etc
If your inputs aren't huge, you could use
perl -0777 -pe 's/\n/\\\n/g'
instead to read the entire input at once instead of line by line, which can be more efficient.
how to replace newline charackters with a string in sed
It's not possible. From sed script point of view, the trailing line missing or not makes no difference and is undetectable.
Aaaanyway, use GNU sed with sed -z:
sed -z 's/\n/\\\n/g'
GNU awk can use the RT variable to detect a missing record terminator:
$ printf 'a\nb\n' | gawk '{ORS=(RT != "" ? "\\" : "") RT} 1'
a\
b\
$ printf 'a\nb' | gawk '{ORS=(RT != "" ? "\\" : "") RT} 1'
a\
b$
This adds a "\" before each non-empty record terminator.
Using any awk:
$ printf 'a\nb\n\n' | awk '{printf "%s%s", sep, $0; sep="\\\n"}'
a\
b\
$ printf 'a\nb\n' | awk '{printf "%s%s", sep, $0; sep="\\\n"}'
a\
b$
Or { cat file; echo; } | awk ... – always add a newline to the input.
Stuck trying to figure out how to single quotes withing single quotes within double quotes. Here's what I'm trying to do....
From perl, I want to run a system command that...
- does an ssh into a remote machine
- executes 'uptime' and then plucks the last field out of that (avg load last 15 min).
\#\!/usr/bin/env perl
my $cmd = "ssh othermachine 'uptime | awk '{print $NF}'' > local_file.dat";
system($cmd);
Of course this won't run ...
% ./try.pl
Missing }.
%
Missing "}" ??? Looks like it's interpreting the $NF} as a var? I tried escaping the {} chars with no luck. I tried escaping the $, no luck. I tried a space before the }, no luck but different msg (Undefined variable).
c-shell BTW and thanks in advance !
You want the following to be ssh's second argument:
uptime | awk '{print $NF}'
To do that, you simply placed single quotes around it. But that doesn't work because it contains single quotes.
You want to build a string that contains $NF, but you did it as follows:
"...$NF..."
That will place the value of (non-existent) Perl variable $NF in the string.
Do it step by step.
Static:
Remote command:
uptime | awk '{print $NF}'
Local command:
ssh othermachine 'uptime | awk '\''{print $NF}'\''' >local_file.dat
String literal:
my $local_cmd = q{ssh othermachine 'uptime | awk '\''{print $NF}'\''' >local_file.dat}
Dynamic:
use String::ShellQuote qw( shell_quote );
my $remote_cmd = q{uptime | awk '{print $NF}'};
my $local_cmd = shell_quote('ssh', 'othermachine', $remote_cmd) . ' >local_file.dat';
Use Net::OpenSSH and let it do the quoting for you:
use Net::OpenSSH;
my $ssh = Net::OpenSSH->new($othermachine,
remote_shell => 'tcsh');
$ssh->system({stdout_file => 'local_file.dat'},
'uptime', \\'|', 'awk', '{print $NF}')
or die "ssh command failed: " . $ssh->error;
I have the following line in a Perl script:
my $temp = `sed 's/ /\n/g' /sys/bus/w1/devices/w1_bus_master1/10-000802415bef/w1_slave | grep t= | sed 's/t=//'`;
Which throws up the error:
"sed: -e expression #1, char 2: unterminated `s' command"
If I run a shell script as below it works fine:
temp1=`sed 's/ /\n/g' /sys/bus/w1/devices/w1_bus_master1/10-000802415bef/w1_slave | grep t= | sed 's/t=//'`
echo $temp1
Anyone got any ideas?
Perl interpretes your \n as a literal newline character. Your command line will therefore look something like this from sed's perspective:
sed s/ /
/g ...
which sed doesn't like. The shell does not interpret it that way.
The proper solution is not to use sed/grep in such a situation at all. Perl is, after all, very, very good at handling text. For example (untested):
use File::Slurp;
my #lines = split m/\n/, map { s/ /\n/g; $_ } scalar(read_file("/sys/bus...));
#lines = map { s/t=//; $_ } grep { m/t=/ } #lines;
Alternatively escape the \n once, e.g. sed 's/ /\\n/g'....
You need to escape the \n in our first regular expression. The backtick-operator in perl thinks it is a control-character and inserts a newline instead of the string \n.
|
V
my $temp = `sed 's/ /\\n/g' /sys/bus/ # ...
I am having trouble on stripping characters within a filename.
For example:
1326847080_MUNDO-Cinco-Cosas-Que-Aprendimos-Del-Debate-De-Los-Republicanos-1.xml
1326836220_PLANETACNN-Una-Granja-De-Mariposas-Ayuda-A-Reducir-La-Tala-De-Bosques-En-Tanzania-3.xml
This is the output I want:
1326847080_MUNDO-1.xml
1326836220_PLANETACNN-3.xml
for i in *.xml
do
j=$(echo $i | sed -e s/-.*-/-/)
echo mv $i $j
done
or in one line:
for i in *.xml; do echo mv $i $(echo $i | sed -e s/-.*-/-/); done
remove echo to actually perform the mv command.
Or, without sed, using bash builtin pattern replacement:
for i in *.xml; do echo mv $i ${i//-*-/-}; done
rename to the rescue, with Perl regular expressions. This command will show which moves will be made; just remove -n to actually rename the files:
$ rename -n 's/([^-]+)-.*-([^-]+)/$1-$2/' *.xml
1326836220_PLANETACNN-Una-Granja-De-Mariposas-Ayuda-A-Reducir-La-Tala-De-Bosques-En-Tanzania-3.xml renamed as 1326836220_PLANETACNN-3.xml
1326847080_MUNDO-Cinco-Cosas-Que-Aprendimos-Del-Debate-De-Los-Republicanos-1.xml renamed as 1326847080_MUNDO-1.xml
The regular expression explained:
Save the part up to (but excluding) the first dash as match 1.
Save the part after the last dash as match 2.
Replace the part from the start of match 1 to the end of match 2 with match 1, a dash, and match 2.
sorry for the late reply , but i saw it today :( .
I think you are looking for the following
input file ::
cat > abc
1326847080_MUNDO-Cinco-Cosas-Que-Aprendimos-Del-Debate-De-Los-Republicanos-1.xml
1326836220_PLANETACNN-Una-Granja-De-Mariposas-Ayuda-A-Reducir-La-Tala-De-Bosques-En-Tanzania-3.xml
code : (its a bit too basic , even for my liking)
while read line
do
echo $line ;
fname=`echo $line | cut -d"-" -f1`;
lfield=`echo $line | sed -n 's/\-/ /gp' | wc -w`;
lname=`echo $line | cut -d"-" -f${lfield}`;
new_name="${fname}-${lname}";
echo "new name is :: $new_name";
done < abc ;
output ::
1326847080_MUNDO-Cinco-Cosas-Que-Aprendimos-Del-Debate-De-Los-Republicanos-1.xml
new name is :: 1326847080_MUNDO-1.xml
1326836220_PLANETACNN-Una-Granja-De-Mariposas-Ayuda-A-Reducir-La-Tala-De-Bosques-En-Tanzania-3.xml
new name is :: 1326836220_PLANETACNN-3.xml
I’d like to write a Perl one-liner to decode a line of ASCII characters encoded as hexadecimal numbers (for example the line 48 54 54 50 should be decoded as HTTP). I came up with this:
perl -nE 'say map(chr, map { qq/0x$_/ } split)'
It prints an empty line. What am I doing wrong and how would you write it?
It's your qq/0x$_/ trick that doesn't work. chr expects a number as argument, but gets the string literal "0x48". Use the hex function to convert 48 to a decimal number, like datageist does in his answer.
This works for me:
echo '48 54 54 50' | perl -nE 'say map(chr, map { hex } split)'
This works:
echo '48 54 54 50' | perl -nE 'say map{chr(hex)} split'
I’m assuming you want to feed the data from STDIN.
As always with Perl TIMTOWTDI.
I thought I would submit several options, and show what they would look like if they were written normally. If you want to know more about the command line options perldoc perlrun is a useful resource.
These all output the same thing. With the exception that some of them don't print a newline on the end.
echo '48 54 54 50' | perl -0x20 -pe'$_=chr hex$_'
echo '48 54 54 50' | perl -0x20 -ne'print chr hex$_'
echo '48 54 54 50' | perl -0777 -anE'say map chr,map hex,#F'
echo '48 54 54 50' | perl -0777 -anE'say map{chr hex$_}#F'
echo '48 54 54 50' | perl -0apple'$_=chr hex$_' -0x20
echo '48 54 54 50' | perl -apple'$_=join"",map{chr hex}#F'
echo '48 54 54 50' | perl -lanE'say map{chr hex}#F'
The following is what some of the examples would look like if they were written normally. If you want to figure out what the rest of them do, definitely look at perldoc perlrun.
perl -0x20 -pe'$_=chr hex$_'
This is one is fairly straight forward. It is perhaps the best example here, and is also the shortest one. It pretends that spaces are used to separate lines, so that there is only one letter to deal with inside of the loop.
# perl -0x20 -pe'$_=chr hex$_'
$/ = " "; # -0 ( input separator )
while( <> ){
$_ = chr hex $_;
} continue {
print $_;
}
perl -0apple'$_=chr hex$_' -0x20
This one has a few command line options that don't do anything useful.
The first -0 option is there so that -l sets the output separator to an empty string.
Which is actually the default for the output separator.
There are two -p options where one would have sufficed.
The -a option sets up the #F array, but we don't actually use it.
Basically I used -a -l and a second -p so that the options would spell apple. Otherwise this one is the same as the last example.
echo '48 54 54 50' | perl -0x20 -pe'$_=chr hex$_'
# perl -0apple'$_=chr hex$_' -0x20
$/ = ""; # -0 ( input separator )
$\ = $/; # -l ( output separator )
$/ = " "; # -0x20 ( input separator )
while( <> ){
#F = split " ", $_; # -a ( unused )
$_ = chr hex $_;
} continue {
print $_;
}
perl -lanE'say map{chr hex}#F'
I figured I already spelled apple, I might as well spell lanE.
-l isn't really useful, because we already are using say.
Used -E instead of -e so that we could use say.
# perl -lanE'say map{chr hex}#F'
$\ = $/; # -l ( output separator set to "\n" )
while( <> ){
#F = split " ", $_; # -a
say map { chr hex $_ } #F;
}
Play perlgolf?
-ple y/0-9A-Fa-f//cd;$_=pack"H*",$_
-ple $_=pack"H*",$_,join"",split
-nE say map chr hex,split
-naE say map chr hex,#F