Probably an easy question but I am not able to figure it out. How can I use sed to replace differently for different occurrences?
I will give an example:
a="2012_01_01_05_05_05"
desired output:
mod_a="2012-01-01 05:05:05"
the only thing I know how to do with sed is:
mod_a=`echo $a | sed 's/_/ /g'`
I could do this by removing the "_", transforming it to an array, and create a new expression based on each element, but it would be less elegant.
this could be the way
mod_a=`echo $a | awk -F_ '{print $1"-"$2"-"$3,$4":"$5":"$6}'`
Simple sed solution:
sed 's/_/-/;s/_/-/;s/_/ /;s/_/:/g' <<< "$a"
It replaces the first and the second _ by -, the third _ by a space and the remaining ones by a :.
Give a try to this GNU sed command,
$ echo '2012_01_01_05_05_05' | sed -r 's/_/-/g;s/^(.*)-([0-9]+)-([0-9]+)-([0-9]+)$/\1 \2:\3:\4/g'
2012-01-01 05:05:05
It replaces all the occurrences of _ with -. From the output it again divides the numbers according to the - and stored it into groups. This groups are backreferenced in the replacement part and formatted according to our desired output.
For your case,
$ mod_a=$(echo $a | sed -r 's/_/-/g;s/^(.*)-([0-9]+)-([0-9]+)-([0-9]+)$/\1 \2:\3:\4/g')
$ echo $mod_a
2012-01-01 05:05:05
You’ve tagged your question bash. If you have GNU Bash why on earth you are trying to use sed to do such a simple thing?
$ a="2012_01_01_05_05_05"
$ IFS='_' read Y m d H M S <<< "$a"
$ mod_a="$Y-$m-$d $H:$M:$S"
$ echo "$mod_a"
2012-01-01 05:05:05
There is nothing elegant in a mess of slashes and dashes which is native to sed but ’write-only’ for human.
Related
I am working on shell script and new to it. I want to extract the string between double $$ characters, for example:
input:
$$extractabc$$
output
extractabc
I used grep and sed but not working out. Any suggestions are welcome!
You could do
awk -F"$" '{print $3}' file.txt
assuming the file contained input:$$extractabc$$ output:extractabc. awk splits your data into pieces using $ as a delimiter. First item will be input:, next will be empty, next will be extractabc.
You could use sed like so to get the same info.
sed -e 's/.*$$\(.*\)$$.*/\1/' file.txt
sed looks for information between $$s and outputs that. The goal is to type something like this .*$$(.*)$$.*. It's greedy but just stay with me.
looks for .* - i.e. any character zero or more times before $$
then the string should have $$
after $$ there'll be any character zero or more times
then the string should have another $$
and some more characters to follow
between the 2 $$ is (.*). String found between $$s is given a placeholder \1
sed finds such information and publishes it
Using grep PCRE (where available) and look-around:
$ echo '$$extractabc$$' | grep -oP "(?<=\\$\\$).*(?=\\$\\$)"
extractabc
echo '$$extractabc$$' | awk '{gsub(/\$\$/,"")}1'
extractabc
Here is an other variation:
echo "$$extractabc$$" | awk -F"$$" 'NF==3 {print $2}'
It does test of there are two set of $$ and only then prints whats between $$
Does also work for input like blabla$$some_data$$moreblabla
How about remove all the $ in the input?
$ echo '$$extractabc$$' | sed 's/\$//g'
extractabc
Same with tr
$ echo '$$extractabc$$' | tr -d '$'
extractabc
I am trying to remove every character in a text string except for the remaining 11 characters. The string is Sample Text_that-would$normally~be,here--pe_-l4_mBY and what I want to end up with is just -pe_-l4_mBY.
Here's what I've tried:
$ cat food
Sample Text_that-would$normally~be,here--pe_-l4_mBY
$ cat food | sed 's/^.*(.{3})$/\1/'
sed: 1: "s/^.*(.{3})$/\1/": \1 not defined in the RE
Please note that the text string isn't really stored in a file, I just used cat food as an example.
OS is macOS High Sierra 10.13.6 and bash version is 3.2.57(1)-release
You can use this sed with a capture group:
sed -E 's/.*(.{11})$/\1/' file
-pe_-l4_mBY
Basic regular expressions (used by default by sed) require both the parentheses in the capture group and the braces in the brace expression to be escaped. ( and { are otherwise treated as literal characters to be matched.
$ cat food | sed 's/^.*\(.\{3\}\)$/\1/'
mBY
By contrast, explicitly requesting sed to use extended regular expressions with the -E option reverses the meaning, with \( and \{ being the literal characters.
$ cat food | sed -E 's/^.*(.{3})$/\1/'
mBY
Try this also:
grep -o -E '.{11}$' food
grep, like sed, accepts an arbitrary number of file name arguments, so there is no need for a separate cat. (See also useless use of cat.)
You can use tail or Parameter Expansion :
string='Sample Text_that-would$normally~be,here--pe_-l4_mBY'
echo "$string" | tail -c 11
echo "${string#${string%??????????}}"
pe_-l4_mBY
pe_-l4_mBY
also with rev/cut/rev
$ echo abcdefghijklmnopqrstuvwxyz | rev | cut -c1-11 | rev
pqrstuvwxyz
man rev => rev - reverse lines characterwise
I have a shell script that accepts a parameter that is comma delimited,
-s 1234,1244,1567
That is passed to a curl PUT json field. Json needs the values in a "1234","1244","1567" format.
Currently, I am passing the parameter with the quotes already in it:
-s "\"1234\",\"1244\",\"1567\"", which works, but the users are complaining that its too much typing and hard to do. So I'd like to just take a comma delimited list like I had at the top and programmatically stick the quotes in.
Basically, I want a parameter to be passed in as 1234,2345 and end up as a variable that is "1234","2345"
I've come to read that easiest approach here is to use sed, but I'm really not familiar with it and all of my efforts are failing.
You can do this in BASH:
$> arg='1234,1244,1567'
$> echo "\"${arg//,/\",\"}\""
"1234","1244","1567"
awk to the rescue!
$ awk -F, -v OFS='","' -v q='"' '{$1=$1; print q $0 q}' <<< "1234,1244,1567"
"1234","1244","1567"
or shorter with sed
$ sed -r 's/[^,]+/"&"/g' <<< "1234,1244,1567"
"1234","1244","1567"
translating this back to awk
$ awk '{print gensub(/([^,]+)/,"\"\\1\"","g")}' <<< "1234,1244,1567"
"1234","1244","1567"
you can use this:
echo QV=$(echo 1234,2345,56788 | sed -e 's/^/"/' -e 's/$/"/' -e 's/,/","/g')
result:
echo $QV
"1234","2345","56788"
just add double quotes at start, end, and replace commas with quote/comma/quote globally.
easy to do with sed
$ echo '1234,1244,1567' | sed 's/[0-9]*/"\0"/g'
"1234","1244","1567"
[0-9]* zero more consecutive digits, since * is greedy it will try to match as many as possible
"\0" double quote the matched pattern, entire match is by default saved in \0
g global flag, to replace all such patterns
In case, \0 isn't recognized in some sed versions, use & instead:
$ echo '1234,1244,1567' | sed 's/[0-9]*/"&"/g'
"1234","1244","1567"
Similar solution with perl
$ echo '1234,1244,1567' | perl -pe 's/\d+/"$&"/g'
"1234","1244","1567"
Note: Using * instead of + with perl will give
$ echo '1234,1244,1567' | perl -pe 's/\d*/"$&"/g'
"1234""","1244""","1567"""
""$
I think this difference between sed and perl is similar to this question: GNU sed, ^ and $ with | when first/last character matches
Using sed:
$ echo 1234,1244,1567 | sed 's/\([0-9]\+\)/\"\1\"/g'
"1234","1244","1567"
ie. replace all strings of numbers with the same strings of numbers quoted using backreferencing (\1).
I am writing shell script for embedded Linux in a small industrial box. I have a variable containing the text pid: 1234 and I want to strip first X characters from the line, so only 1234 stays. I have more variables I need to "clean", so I need to cut away X first characters and ${string:5} doesn't work for some reason in my system.
The only thing the box seems to have is sed.
I am trying to make the following to work:
result=$(echo "$pid" | sed 's/^.\{4\}//g')
Any ideas?
The following should work:
var="pid: 1234"
var=${var:5}
Are you sure bash is the shell executing your script?
Even the POSIX-compliant
var=${var#?????}
would be preferable to using an external process, although this requires you to hard-code the 5 in the form of a fixed-length pattern.
Here's a concise method to cut the first X characters using cut(1). This example removes the first 4 characters by cutting a substring starting with 5th character.
echo "$pid" | cut -c 5-
Use the -r option ("use extended regular expressions in the script") to sed in order to use the {n} syntax:
$ echo 'pid: 1234'| sed -r 's/^.{5}//'
1234
Cut first two characters from string:
$ string="1234567890"; echo "${string:2}"
34567890
pipe it through awk '{print substr($0,42)}' where 42 is one more than the number of characters to drop. For example:
$ echo abcde| awk '{print substr($0,2)}'
bcde
$
Chances are, you'll have cut as well. If so:
[me#home]$ echo "pid: 1234" | cut -d" " -f2
1234
Well, there have been solutions here with sed, awk, cut and using bash syntax. I just want to throw in another POSIX conform variant:
$ echo "pid: 1234" | tail -c +6
1234
-c tells tail at which byte offset to start, counting from the end of the input data, yet if the the number starts with a + sign, it is from the beginning of the input data to the end.
Another way, using cut instead of sed.
result=`echo $pid | cut -c 5-`
I found the answer in pure sed supplied by this question (admittedly, posted after this question was posted). This does exactly what you asked, solely in sed:
result=\`echo "$pid" | sed '/./ { s/pid:\ //g; }'\``
The dot in sed '/./) is whatever you want to match. Your question is exactly what I was attempting to, except in my case I wanted to match a specific line in a file and then uncomment it. In my case it was:
# Uncomment a line (edit the file in-place):
sed -i '/#\ COMMENTED_LINE_TO_MATCH/ { s/#\ //g; }' /path/to/target/file
The -i after sed is to edit the file in place (remove this switch if you want to test your matching expression prior to editing the file).
(I posted this because I wanted to do this entirely with sed as this question asked and none of the previous answered solved that problem.)
Rather than removing n characters from the start, perhaps you could just extract the digits directly. Like so...
$ echo "pid: 1234" | grep -Po "\d+"
This may be a more robust solution, and seems more intuitive.
This will do the job too:
echo "$pid"|awk '{print $2}'
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//'`