I have the following bash:
#!/bin/bash
if ["$#" -ne "1"]; then
echo "Usage: `basename $0` <HOSTNAME>"
exit 1
fi
IPADDR=`ifconfig | head -2 | tail -1 | cut -d: -f2 | rev | cut -c8-23 | rev`
sed -i -e '1i$IPADDR $1\' /etc/hosts
But when I cat /etc/hosts:
$IPADDR
How can I deal with such issues?
Your problem is that variables inside single quotes ' aren't expanded by the shell, but left unchanged. To quote variables you want expanded use double quotes " or just leave off the quotes if they are unneeded like here, e.g.
sed -i -e '1i'$IPADDR' '$1'\' /etc/hosts
In above line $IPADDR and $1 are outside of quotes and will be expanded by the shell before the arguments are being feed to sed.
The single quotes mean the string isn't interpolated as a variable.
#!/bin/bash
IPADDR=$(/sbin/ifconfig | head -2 | tail -1 | cut -d: -f2 | rev | cut -c8-23 | rev)
sed -i -e "1i${IPADDR} ${1}" /etc/hosts
I also did the command in $(...) out of habit!
Refer to sed manual:https://www.gnu.org/software/sed/manual/sed.html
As a GNU extension, the i command and text can be separated into two
-e parameters, enabling easier scripting:
The formal usage should be:
sed -i -e "1i$IPADDR\\" -e "$1" /etc/hosts
Related
I currently am trying to get specific parameters from a url.
My url looks like: https://private.io/report-artifact/dsop-pipeline-artifacts/container-scan-reports/redhat/ubi/ubi7/7.8/2020-02-14T222203.548_2868/ubi7-7.8.tar
I want just redhat/ubi/ubi7/7.8
I can get redhat/ubi/ubi7/7.8/2020-02-14T222203.548_2868/ubi7-7.8.tar by doing,
echo https://private.io/report-artifact/dsop-pipeline-artifacts/container-scan-reports/redhat/ubi/ubi7/7.8/2020-02-14T222203.548_2868/ubi7-7.8.tar | sed 's|.*/container-scan-reports/||'
Thus I want to remove /2020-02-14T222203.548_2868/ubi7-7.8.tar
I also would like to change the / to a - so that I have redhat-ubi-ubi7-7.8
With GNU sed:
Get the 4 following path elements after .*/container-scan-reports/ and replace all / with -:
url='https://private.io/report-artifact/dsop-pipeline-artifacts/container-scan-reports/redhat/ubi/ubi7/7.8/2020-02-14T222203.548_2868/ubi7-7.8.tar'
echo "$url" | sed -E 's|.*/container-scan-reports/(([^/]*/){3}[^/]*).*|\1|;s|/|-|g'
Or you could get everything after .*/container-scan-reports/, but not the last two path elements:
echo "$url" | sed -E 's|.*/container-scan-reports/(.*)/[^/]*/[^/]*|\1|;s|/|-|g'
When you know the position in the string you can use cut
echo "${string}" | cut -d/ -f 7-10 | tr '/' '-'
Another way with sed is
echo "${string}" | sed -E 's#([^/]*/){6}([^/]*)/([^/]*)/([^/]*)/([^/]*).*#\2-\3-\4-\5#'
I have text like:
TEXT="I need to replace the hostname [[google.com]] with it's ip in side the text"
Is there a way to use something like below, but working?
sed -Ee "s/\[\[(.*)\]\]/`host -t A \1 | rev | cut -d " " -f1 | rev`/g" <<< $TEXT
looks like the value of \1 is not being passed to the shell command used inside sed.
Thanks
Backquote interpolation is performed by the shell, not by sed. This means that your backquotes will either be replaced by the output of a command before the sed command is run, or (if you correctly quote them) they will not be replaced at all, and sed will see the backquotes.
You appear to be trying to have sed perform a replacement, then have the shell perform backquote interpolation.
You can get the backquotes past the shell by quoting them properly:
$ echo "" | sed -e 's/^/`hostname`/'
`hostname`
However, in that case you will have to use the resulting string in a shell command line to cause backquote interpolation again.
Depending on how you feel about awk, perl, or python, I'd suggest you use one of them to do this job in a single pass. Alternatively, you could make a first pass extracting the hostnames into a command without backquotes, then execute the commands to get the IP addresses you want, then replace them in another pass.
It's got to be a two part command, one to get a variable that bash can use, the other to do a straight-up /s/ replacement with sed.
TEXT="I need to replace the hostname [[google.com]] with it's ip in side the text"
DOMAIN=$(echo $TEXT | sed -e 's/^.*\[\[//' -e 's/\]\].*$//')
echo $TEXT | sed -e 's/\[\[.*\]\]/'$(host -tA $DOMAIN | rev | cut -d " " -f1 | rev)'/'
But, more cleanly using how to split a string in shell and get the last field
TEXT="I need to replace the hostname [[google.com]] with it's ip in side the text"
DOMAIN=$(echo $TEXT | sed -e 's/^.*\[\[//' -e 's/\]\].*$//')
HOSTLOOKUP=$(host -tA $DOMAIN)
echo $TEXT | sed -e 's/\[\[.*\]\]/'${HOSTLOOKUP##* }/
The short version is that you can't mix sed and bash the way you're expecting to.
This works:
#!/bin/bash
txt="I need to replace the hostname [[google.com]] with it's ip in side the text"
host_name=$(sed -E 's/^[^[]*\[\[//; s/^(.*)\]\].*$/\1/' <<<"$txt")
ip_addr=$(host -tA "$host_name" | sed -E 's/.* ([0-9.]*)$/\1/')
echo "$txt" | sed -E 's/\[\[.*\]\]/'"$ip_addr/"
# I need to replace the hostname 172.217.4.174 with it's ip in side the text
Thank you all,
I made the below solution:
function host_to_ip () {
echo $(host -t A $1 | head -n 1 | rev | cut -d" " -f1 | rev)
}
function resolve_hosts () {
local host_placeholders=$(grep -o -e "##.*##" $1)
for HOST in ${host_placeholders[#]}
do
sed -i -e "s/$HOST/$(host_to_ip $(sed -Ee 's/##(.*)##/\1/g' <<< $HOST))/g" $1
done
}
Where resolve_hosts gets a text file as an argument
I want to insert '.' between every character in a given input string and then use it as an argument in a pipe
I am doing one of the following:
tail -f file.txt | grep -a 'R.e.s.u.l.t.'
tail -f file.txt | awk '/R.e.s.u.l.t./'
How can I just type 'Result' and pass it as the regex argument to grep when
receiving input from a buffer created by tail -f by using additional bash default functions
tail -f file.txt | grep -a -e "$(echo Result | sed 's/./&./g')"
This echoes the word Result as input to sed (consider a here-string instead), which replaces each character with itself followed by a ., and then the output is used as the search expression for grep. The -e protects you from mishaps if you want to search for -argument with the dots, for example. If the string is in a variable, then you'd use double quotes around that, too:
result="Several Words"
tail -f file.txt | grep -a -e "$(echo "$result" | sed 's/./&./g')"
The awk version:
tail -f file.txt |
awk -v word="Result" '
BEGIN {gsub(/./, "&.", word); sub(/\.$/, "", word)}
$0 ~ word
'
I am getting the following output from a bash script:
INFOPLIST_FILE = MajorDomo/MajorDomo-Info.plist
and I would like to get only the path(MajorDomo/MajorDomo-Info.plist) using grep. In other words, everything after the equals sign. Any ideas of how to do this?
This job suites more to awk:
s='INFOPLIST_FILE = MajorDomo/MajorDomo-Info.plist'
awk -F' *= *' '{print $2}' <<< "$s"
MajorDomo/MajorDomo-Info.plist
If you really want grep then use grep -P:
grep -oP ' = \K.+' <<< "$s"
MajorDomo/MajorDomo-Info.plist
Not exactly what you were asking, but
echo "INFOPLIST_FILE = MajorDomo/MajorDomo-Info.plist" | sed 's/.*= \(.*\)$/\1/'
will do what you want.
You could use cut as well:
your_script | cut -d = -f 2-
(where your_script does something equivalent to echo INFOPLIST_FILE = MajorDomo/MajorDomo-Info.plist)
If you need to trim the space at the beginning:
your_script | cut -d = -f 2- | cut -d ' ' -f 2-
If you have multiple spaces at the beginning and you want to trim them all, you'll have to fall back to sed: your_script | cut -d = -f 2- | sed 's/^ *//' (or, simpler, your_script | sed 's/^[^=]*= *//')
Assuming your script outputs a single line, there is a shell only solution:
line="$(your_script)"
echo "${line#*= }"
Bash
IFS=' =' read -r _ x <<<"INFOPLIST_FILE = MajorDomo/MajorDomo-Info.plist"
printf "%s\n" "$x"
MajorDomo/MajorDomo-Info.plist
I need to replace characters from 10th to 20th in the string which looks like that:
123456789012345678901234567890
So far I've tried:
a)
Works for the 10th character ONLY:
echo "123456789012345678901234567890" | sed 's/./X/10'
b)
Doesn't work on the range:
echo "123456789012345678901234567890" | sed 's/./X/10,20'
echo "123456789012345678901234567890" | sed 's/./X/10\,20'
echo "123456789012345678901234567890" | sed 's/./X/\{10,20\}'
echo "123456789012345678901234567890" | sed 's/./X/\{10\,20\}'
Does not work and I get error
unknown option to `s'
So - the question is - how do I make this to work:
echo "123456789012345678901234567890" | sed 's/./X/10,20'
Try:
$ sed -r "s/^(.{9})(.{11})/\1XXXXXXXXXX/" <<< 123456789012345678901234567890
123456789XXXXXXXXXX1234567890
It is a complex sed problem, I could just find this solution:
$ sed 's/^\(.\{10\}\)\(.\{10\}\)/\1XXXXXXXXXX/' <<< 123456789012345678901234567890
1234567890XXXXXXXXXX1234567890
With awk it looks nicer:
$ awk 'BEGIN{FS=OFS=""} {for (i=10;i<=20;i++) $i="X"} {print}' <<< 123456789012345678901234567890
123456789XXXXXXXXXXX1234567890
You can do it with bash parameter substitution like this:
#!/bin/bash
s="123456789012345678901234567890"
l=${s:0:9} # Extract left part
m=${s:10:11} # Extract middle part
r=${s:20} # Extract right part
# Diddle with middle part to your heart's content and re-assemble "$l$m$r" when done
m=$(sed 's/./X/g' <<<$m)
See here for more explanation and examples.
Or, you can do this:
transform the row of letters into a column so each is on its own line
apply your edits to LINES 10 through 20 (as opposed to characters 10 through 20)
transform column of letters back into a row (by deleting linefeeds)
as shown in the one-liner below:
$ echo "123456789012345678901234567890" | sed "s/\(.\)/\1\n/g" | sed "10,20s/./X/" | tr -d "\n"
I know, that it looks ugly, but:
echo "123456789012345678901234567890" | \
sed 's/^\(.\{10\}\).\{10\}\(.*\)/\1XXXXXXXXXX\2/'
Without placing multiple X in sed command:
sed -r 's/^(.{9})(.{10,20})(.*)$/\1\n\2\n\3/' | sed -e '2s/./X/g' -e 'N;N;s/\n//g'
To replace the 10th to 20th characters, inclusive, try:
echo 123456789012345678901234567890 | sed 's/\(.\{9\}\).\{11\}/\1XXXXXXXXXX/'
123456789XXXXXXXXXX1234567890
With the GNU sed, you can use the -r switch to remove most of the backslashes:
echo 123456789012345678901234567890 | sed -r 's/(.{9}).{11}/\1XXXXXXXXXX/'
Or the naive approach also works here:
echo 123456789012345678901234567890 | sed 's/\(.........\).........../\1XXXXXXXXXX/'
This might work for you (GNU sed):
sed ':a;/.\{9\}X\{11\}/!s/\(.\{9\}X*\)./\1X/;ta' file
or with a bit of syntactic sugar:
sed -r ':a;/.{9}X{11}/!s/(.{9}X*)./\1X/;ta' file