Using the Terminal on Mac, I need to find and display only the MAC addresses with a line break following each address.
ifconfig | grep 'ether ' | cut -b 7-24
returns
38:c9:86:3c:ed:16
28:f0:76:3c:c2:e4
1a:00:01:87:0d:30
1a:00:01:87:0d:31
3a:c9:86:c3:c8:00
0a:f0:76:3c:c2:e4
5e:05:5b:91:c5:99
What command can I use that will put a line break after each address?
Normally, I would use sed to replace a character, but I've never been able to find a way for sed to insert newline characters.
To get the output you want, you would have to insert 2 newlines at the end of each line:
for i in $(ifconfig |grep 'ether' |awk '{print $2}'); do printf
"$i\n\n"; done
Output:
38:c9:86:3c:ed:16
28:f0:76:3c:c2:e4
1a:00:01:87:0d:30
1a:00:01:87:0d:31
3a:c9:86:c3:c8:00
0a:f0:76:3c:c2:e4
5e:05:5b:91:c5:99
Related
I run the command
df -gP /data1 /data2 | grep -v File | awk '{print $1}' |
awk -F/dev/ '$0=$2' | tr '\n' '
on the AIX shell (ksh) and it prints the output below:
lv_data01 lv_data02 root#testhost:/
However, I would like the output to be printed this way. Could someone help?
lv_data01 lv_data02
Using grep … | awk … | awk … is not necessary; a single awk could do the whole job. So could sed and it might even be easier. I'd be tempted to deal with the spacing by using:
x=$(df … | sed …); echo $x
The tr command, once corrected, replaces newlines with spaces, so the prompt follows without a newline before it. The ; echo suggestion adds the missing newline; the echo $x suggestion (note no double quotes) does too.
As for the sed command:
sed -n '/File/!{ s/[[:space:]].*//; s%^.*/dev/%%p; }'
Don't print anything by default
If the line doesn't match File (doing the work of grep -v):
remove the first space (blank or tab) and everything after it (doing the work of awk '{print $1}')
replace everything up to /dev/ with nothing and print (doing the work of awk -F/dev/ '{$0=$2}')
The command substitution and capture, followed by echo, deals with spaces and newlines.
So, my suggested solution is:
x=$(df -gP /data1 /data2 | sed -n '/File/!{ s/[[:space:]].*//; s%^.*/dev/%%p; }'); echo $x
You could add unset x after the echo if you are going to be using this directly in the shell and not in a shell script. If it'll be encapsulated in a shell script, you don't have to worry about it.
I'm blithely assuming the output from df -gP won't contain a path such as this, with two occurrences of /dev:
/who/knows/dev/lv_data01/dev/bin
If that's a real problem, you can fix the sed script, but I don't think it will be. It's one thing the second awk script in the question handles differently.
i want to trim a textfile and delete all lines from line n to the end of the file. I tried to use sed for that. The sed command for n=26 should look like that:
sed -i '26,$d' /path/to/textfile
So in my textfile i don't know n beforehand, but i know that there is a unique text in that line. So i tried it that way:
myvar=`grep -n 'unique text' /path/to/textfile | awk -F":" '{print $1 }'`
sed -i "${myvar}"',$d' /path/to/textfile
That works and deletes all wanted lines but it throws the error message:
sed: -e expression # 1, character 1: unknown command: »,«
So i tried changing my command to:
myvar=`grep -n 'unique text' /path/to/textfile | awk -F":" '{print $1 }'`
sed -i "${myvar},$d" /path/to/textfile
With that i get the same error message but it doesn't delete the lines.
I tried some variations with ' and " and how to put the variable in there, but it never works as wanted. Does someone knows what i do wrong?
I would appreciate other methods for trimming the textfile as long as i can do it in a bash script.
You can replace the fixed line number with a regular expression matching the line to start at.
sed -i '/unique text/,$d' /path/to/textfile
You can also use ed to edit the file, rather than rely on a non-standard sed extension.
printf '/unique text/,$d\nwq\n' | ed /path/to/textfile
i'm trying to extract a specific string from a grep output
uci show minidlna
produces a large list
.
.
.
minidlna.config.enabled='1'
minidlna.config.db_dir='/mnt/sda1/usb/db'
minidlna.config.enable_tivo='1'
minidlna.config.wide_links='1'
.
.
.
so i tried to narrow down what i wanted by running
uci show minidlna | grep -oE '\bdb_dir=\S+'
this narrows the output to
db_dir='/mnt/sda1/usb/db'
what i want is to output only
/mnt/sda1/usb/db
without the quotes and without the starting "db_dir" so i can run rm /mnt/sda1/usb/db/file.db
i've used the answers found here
How to extract string following a pattern with grep, regex or perl
and that's as close as i got.
EDIT: after using Ed Morton's awk command i needed to pass the output to rm command.
i used:
| ( read DB; (rm $DB/files.db) .
read DB passes the output into the vairable DB.
(...) combines commands.
rm $DB/files.db deletes the the file files.db.
Is this what you're trying to do?
$ awk -F"'" '/db_dir/{print $2}' file
/mnt/sda1/usb/db
That will work in any awk in any shell on every UNIX box.
If that's not what you want then edit your question to clarify your requirements and post more truly representative sample input/output.
Using sed with some effort to avoid single quotes:
sed -n 's/^minidlna.config.db_dir=\s*\S\(\S*\)\S\s*$/\1/p' input
Well, so you end up having a string like db_dir='/mnt/sda1/usb/db'.
I would first remove the quotes by piping this to
.... | tr -d "'"
Now you end up with a string like db_dir=/mnt/sda1/usb/db.
Say you have this string stored in a variable named confstr, then
${confstr##*=}
gives you just /mnt/sda1/usb/db, since *= denotes everything from the start to the equal sign, and ## denotes removal.
I would do this:
Once you either extracted your line about into file.txt (or pipe it into this command), split the fields using the quote character. Use printf to generate the rm command and pass this into bash to execute.
$ awk -F"'" '{printf "rm %s.db/file.db\n", $2}' file.txt | bash
rm: /mnt/sda1/usb/db.db/file.db: No such file or directory
With your original command:
$ uci show minidlna | grep -oE '\bdb_dir=\S+' | \
awk -F"'" '{printf "rm %s.db/file.db\n", $2}' | bash
I need to parse the line written bold below:
line="eth1 Link encap:Ethernet HWaddr 11:11:11:11:11:11"
This line may have more words unexpectedly such as
line="eth1 Link encap:Ethernet Extra HWaddr 11:11:11:11:11:11"
So, for parsing the MAC address correctly, I need to parse the line accordingly with a bash command.
echo $line | cut -d' ' -f5* works for the first line, while *echo $line | cut -d' ' -f6* works for the second. So, I need to parse only the last column of the line.
However, because of the device restriction, I can only use grep and cut command. Not sed, awk, rev,reverse, etc.
With grep:
echo $line | grep -o -E '[^ ]+$'
With cut, a solution can be made with an extra computation based on the word count, assuming the delimiter is a space:
nw=$(echo $line | wc -w)
echo $line | cut -d ' ' -f$nw-
If the MAC address is the last sequence of characters after a space, you can remove the longest match of "* " (asterisk and a space) pattern using pure Bash:
echo "${line##* }"
You can also extract the last 17 characters from the string:
echo "${line: -17}"
If you want a strict match at the end of the line (due to .*):
echo $(expr match "$line" '.*\(\([a-zA-Z0-9]\{2\}\:\)\{5\}[a-zA-Z0-9]\{2\}\)')
Using GNU grep:
grep -o -P '(?:[a-zA-Z0-9]{2}:){5}[a-zA-Z0-9]{2}' <<< "$line"
In the latter case, you may want to add the $ anchor for the end of the line. Of course, you don't have to use here string. You may want to use a pipe instead: echo "$line" | grep -o -P ....
I have this peace of code:
cat BP.csv | while read line ; do
goterm=$(awk '{print $1}') ;
name=$(awk '{print $2}') ;
grep -w "$goterm" GOEA.csv | sed "s/$goterm/pi/g" ;
done
file BP.csv has this format:
GO:0008283 cell proliferation
GO:0009405 pathogenesis
GO:0010201 response to continuous far red light stimulus by the high-irradiance response system
GO:0009641 shade avoidance
while GOEA.csv has this format:
4577 GO:0006807 0.994 2014_06_01
4577 GO:0016788 0.989 2014_06_01
4577 GO:0043169 0.977 2014_06_01
4577 GO:0043170 0.963 2014_06_01
sed doesn't work. I want to change GO:0043170 for example, to string "pi", but it gives:
sed: -e expression #1, char 12: unterminated `s' command
Why?
Thanks.
You running your awk command against no input, Try this:
cat BP.csv | while read line ; do
goterm=$(awk '{print $1}' <<< "$line") ;
name=$(awk '{print $2}' <<< "$line" ) ;
grep -w "$goterm" GOEA.csv | sed "s/$goterm/pi/g" ;
done
Let's clean up this code a bit:
while read goterm name
do
grep -w "$goterm" GOEA.csv | sed "s/$goterm/pi/g"
done < BP.cvs
The problem is that your awk statements are attempting to read in from STDIN just like your while is doing. You're reading from the same input stream.
What you want to do is to pull out the values from your line. I'm using read to do this. The read statement uses the values in $IFS to separate out the input. This is normally spaces, tabs, and newlines. The read reads each variable you put on the line, and the last value read in contains the entire rest of the line.
Thus:
while read line
reads in the entire line while:
while goterm name
will break the line as
goterm="GO:0008283"
name="cell proliferation"
One more thing. When you use grep and sed together, you probably can get away with just sed:
while read goterm name
do
sed -n "/$goterm/s/$goterm/pi/gp" GOEA.csv
done < BP.csv
The format for the sed command is:
/lines/command/parameters/
So, I'm searching for lines with $goterm in them, then I am replacing $goterm with pi. The -n means don't print out the lines as sed processes them and p means to print out the lines were the substitute is located.
By the way, csv as a file suffix means comma separated values but neither file looks like it is comma separated. Are these tabs separating each field. If so, you'll need to modify $IFS to be tabs.
I would restructure that whole thing more like this:
while read goterm restofline
do
grep -w "${goterm}" GOEA.csv | sed -e "s/${goterm}/pi/g"
done < BP.csv
No reason for the awk things, as the bash read builtin will do rudimentary field splitting for you if you give it multiple variables. Also, you aren't using name anyway, so it's not needed. cat is unnecessary as well.
Depending on your exact use case, even the grep may be unnecessary, making the inner command simply sed -ne "s/${goterm}/pi/gp" GOEA.csv. Unless your purpose for the grep -w is eliminating lines where ${goterm} is a substring of a word instead of the whole word...
For future reference, inserting a set -x above your loop in your script would show you the exact commands that are being run, so that you can compare them with your expectations.