I am writing a script that will do some automated things, and it requires to be put in the format <tld>_<site>_<sub> for now.
I will basically provoke it as such: ./add.sh about.site.com
Which will add the corresponding entries once the name is extracted
How could I write this?
You can mess with $IFS to change how things like read parse text:
hostname="foo.bar.com"
IFS=. read sub site tld <<< "$hostname"
echo ${tld}_${site}_${sub}
Or awk (a little cleaner than sed):
echo $1 | awk -F"." '{print $3 "_" $2 "_" $1}'
You could also use sed:
echo $1 | sed 's/\([^.]*\)\.\([^.]*\)\.\([^.]*\)/\3.\2.\1/'
Lots of backslashes, and it involves two processes, but it could have advantages if you need to handle many such substitutions in a single invocation of the script.
Related
sed terminating early because of escape characters in variables. Hoping awk can do what I need but can't see how!
# Main section ==========================================╕
LASTIP=`grep -E '[0-2]{0,1}[0-9]{0,9}[0-9]{0,1}\.[0-2]{0,1}[0-9]{0,9}[0-9]{0,1}\.[0-2]{0,1}[0-9]{0,9}[0-9]{0,1}\.[0-2]{0,1}[0-9]{0,9}[0-9]{0,1}' $SRCDIR/$IPLOGFILE | tail -1|awk -F'\t' '{print$3}'`
if [ "$CURRENTIP" == "$LASTIP" ]; then
# Still using old IP===================================╕
FIRSTDETECTED=`grep $LASTIP $SRCDIR/$IPLOGFILE | tail -1|awk -F'\t' '{print$1}'`
LASTDETECTED=`grep $LASTIP $SRCDIR/$IPLOGFILE | tail -1|awk -F'\t' '{print$2}'`
OLDLINE=$(printf "$FORMAT" "$FIRSTDETECTED" "$LASTDETECTED" "$LASTIP")
AMENDEDLINE=$(printf "$FORMAT" "$FIRSTDETECTED" "$TIMESTAMP" "$LASTIP")
sed -i "s/'$OLDLINE'/'$AMENDEDLINE'/g" $SRCDIR/$IPLOGFILE
This works fine apart from the last sed, which terminates because $OLDLINE and/or $AMENDEDLINE contains escape chars. I thought I could do a direct substitution for awk to solve the issue but the more I thought about it the more I thought the whole section could be done much more efficiently with awk - maybe in one line of awk? Trouble is I don't know where to start. Am I fooling myself about simplifying it or is there a way? If there is, you may have to help me out, as I find this stuff 'warps my fragile little mind'*
*courtesy of Cartman ;P
I've snipped out the section but can supply the rest of the script if that helps?
You can perhaps try like that
sed -i 's/'"$OLDLINE"'/'"$AMENDEDLINE"'/g' "$SRCDIR"/"$IPLOGFILE"
I think '$OLDLINE' and '$AMENDEDLINE' are not expanded
I have a CSV list that is two columns (col1 is Share Name, col2 is file system path). I need two variables for either everything BEFORE the comma, or everything AFTER the column. My issue is that either column potentially has spaces, and even though these are quoted in the output, my script isn't handling them properly.
CSV:
ShareName,/path/to/sharename
"Share with spaces",/path/to/sharewithspaces
ShareWithSpace,"/path/to/share with spaces"
I was using this awk statement to get either field 1 or field 2:
echo $line | awk -F "\"*,\"*" '{print $2}'
BUT, I soon realized that it wasn't handling the spaces properly, even when passing that command to a variable and quoting the variable.
So, then after googling my brain out, I was trying this:
echo $line | cut -d, -f2
Which works, EXCEPT when echoing the variable $line. If I echo the string, it works perfectly, but unfortunately I'm using this in a while/read/do.
I am fairly certain my issue is having to define fields and having whitespace, but I really only need before or after a comma.
Here's the stripped down version so there's no sensitive data.
#!/usr/bin/bash
ssh <ip> <command> > "2_shares.txt"
<command> > "1_shares.txt"
file1="1_shares.txt"
file2="2_shares.txt"
while read -r line
do
share=`echo "$line" | awk -F "\"*,\"*" '{print $1}'`
path=`echo "$line" | awk -F "\"*,\"*" '{print $2}'`
if grep "$path" $file2 > /dev/null;
then
:
else
echo "SHARE NEEDS CREATED FOR $line"
case $path in
*)
blah blah blah
;;
esac
fi
done < "$file1"
You could simply do like this,
awk -F',' '{print $2}' file
To skip the first line.
awk -F',' 'NR>1{print $2}' file
Your issue is simply that you aren't quoting your shell variables. ALWAYS quote shell variables unless you have a very specific reason not to and are fully aware of all of the consequences.
I strongly suspect the rest of your script is completely wrong in it's approach since you apparently didn't know to quote variables and are talking about shell loops and echoing one line at time to awk so please do post a followup question if you'd like help.
How can I pass the output of awk to a for file in loop?
for file in awk '{print $2}' my_file; do echo $file done;
my_file contains the name of the files whose name should be displayed (echoed).
I get just a
>
instead of my normal prompt.
Use backticks or $(...) to substitute the output of a command:
for file in $(awk '{print $2}' my_file)
do
echo "$file"
done
for file in $(awk '{print $2}' my_file); do echo "$file"; done
The notation to use is $(...) or Command Substitution.
for file in $(awk '{print $2}' my_file)
do
echo $file
done
Where I assume that you do more in the body of the loop than just echo since you could then leave the loop out altogether:
awk '{print $2}' my_file
Or, if you miss typing semicolons and don't like to spread code over multiple lines for readability, then you can use:
for file in $(awk '{print $2}' my_file); do echo $file; done
You will also find in (mostly older) code the backticks used:
for file in `awk '{print $2}' my_file`
do
echo $file
done
Quite apart from being difficult to use in the Markdown used to format comments (and questions and answers) on Stack Overflow, the backticks are not as friendly, especially when nested, so you should recognize them and understand them but not use them.
Incidentally, the reason you got the > prompt is that this command line:
for file in awk '{print $2}' my_file; do echo $file done;
is missing a semicolon before the done. The shell was still waiting for the done. Had you typed done and return, you would have seen the output:
awk done
{print $2} done
my_file done
Using backticks or $(awk ...) for command substitution is an acceptable solution for a small number of files; however, consider using xargs for single commands or pipes or a simple while read ... for more complex tasks (but it will work for simple ones too)
awk '...' |while read FILENAME; do
#do work with each file here using $FILENAME
done
This will allow processing to be done as each filename is processed instead of having to wait for the whole awk script to complete and allow for a larger set of filenames (you can only give so many args to a for x in ...; do) This will typically speed up your scripts and allow the same kinds of operations you would get in a for in loop without its limitations.
I wanted to print the name from the entire address by shell scripting. So user1#12.12.23.234 should give output "user1" and similarly 11234#12.123.12.23 should give output 11234
Reading from the terminal:
$ IFS=# read user host && echo "$user"
<user1#12.12.23.234>
user1
Reading from a variable:
$ address='user1#12.12.23.234'
$ cut -d# -f1 <<< "$address"
user1
$ sed 's/#.*//' <<< "$address"
user1
$ awk -F# '{print $1}' <<< "$address"
user1
Using bash in place editing:
EMAIL='user#server.com'
echo "${EMAIL%#*}
This is a Bash built-in, so it might not be very portable (it won't run with sh if it's not linked to /bin/bash for example), but it is probably faster since it doesn't fork a process to handle the editing.
Using sed:
echo "$EMAIL" | sed -e 's/#.*//'
This tells sed to replace the # character and as many characters that it can find after it up to the end of line with nothing, ie. removing everything after the #.
This option is probably better if you have multiple emails stored in a file, then you can do something like
sed -e 's/#.*//' emails.txt > users.txt
Hope this helps =)
I tend to use expr for this kind of thing:
address='user1#12.12.23.234'
expr "$address" : '\([^#]*\)'
This is a use of expr for its pattern matching and extraction abilities. Translated, the above says: Please print out the longest prefix of $address that doesn't contain an #.
The expr tool is covered by Posix, so this should be pretty portable.
As a note, some historical versions of expr will interpret an argument with a leading - as an option. If you care about guarding against that, you can add an extra letter to the beginning of the string, and just avoid matching it, like so:
expr "x$address" : 'x\([^#]*\)'
I am a newbie in Bash and I am doing some string manipulation.
I have the following file among other files in my directory:
jdk-6u20-solaris-i586.sh
I am doing the following to get jdk-6u20 in my script:
myvar=`ls -la | awk '{print $9}' | egrep "i586" | cut -c1-8`
echo $myvar
but now I want to convert jdk-6u20 to jdk1.6.0_20. I can't seem to figure out how to do it.
It must be as generic as possible. For example if I had jdk-6u25, I should be able to convert it at the same way to jdk1.6.0_25 so on and so forth
Any suggestions?
Depending on exactly how generic you want it, and how standard your inputs will be, you can probably use AWK to do everything. By using FS="regexp" to specify field separators, you can break down the original string by whatever tokens make the most sense, and put them back together in whatever order using printf.
For example, assuming both dashes and the letter 'u' are only used to separate fields:
myvar="jdk-6u20-solaris-i586.sh"
echo $myvar | awk 'BEGIN {FS="[-u]"}; {printf "%s1.%s.0_%s",$1,$2,$3}'
Flavour according to taste.
Using only Bash:
for file in jdk*i586*
do
file="${file%*-solaris*}"
file="${file/-/1.}"
file="${file/u/.0_}"
do_something_with "$file"
done
i think that sed is the command for you
You can try this snippet:
for fname in *; do
newname=`echo "$fname" | sed 's,^jdk-\([0-9]\)u\([0-9][0-9]*\)-.*$,jdk1.\1.0_\2,'`
if [ "$fname" != "$newname" ]; then
echo "old $fname, new $newname"
fi
done
awk 'if(match($9,"i586")){gsub("jdk-6u20","jdk1.6.0_20");print $9;}'
The if(match()) supersedes the egrep bit if you want to use it. You could use substr($9,1,8) instead of cut as well.
garph0 has a good idea with sed; you could do
myvar=`ls jdk*i586.sh | sed 's/jdk-\([0-9]\)u\([0-9]\+\).\+$/jdk1.\1.0_\2/'`
You're needing the awk in there is an artifact of the -l switch on ls. For pattern substitution on lines of text, sed is the long-time champion:
ls | sed -n '/^jdk/s/jdk-\([0-9][0-9]*\)u\([0-9][0-9]*\)$/jdk1.\1.0_\2/p'
This was written in "old-school" sed which should have greater portability across platforms. The expression says:
don't print lines unless they match -n
on lines beginning with 'jdk' do:
on a line that contains only "jdk-IntegerAuIntegerB"
change it to "jdk.1.IntegerA.0_IntegerB"
and print it
Your sample becomes even simpler as:
myvar=`echo *solaris-i586.sh | sed 's/-solaris-i586\.sh//'`