CODEWITHSUNDEEP
unix
Ankita Yadav
Ankita Yadav

Reputation: 33

command in shell to get second numeric value after "-"

Example

prod2-03_dl-httpd-prod-8080_access_referer_log.20181111-050000

I need value 8080. So basically we need digit value after second occurrence of '-'.

We tried following options:

echo "prod2-03_dl-httpd-prod-8080_access_referer_log.20181111-050000" | sed -r 's/([^-][:digit:]+[^-][:digit:]).*/\1/'

Upvotes: 2

Views: 50

Answers (3)

ghoti
ghoti

Reputation: 46856

You could do this in a POSIX shell using IFS to identify the parts, and a loop to step to the pattern you're looking for:

s="prod2-03_dl-httpd-prod-8080_access_referer_log.20181111-050000"

# Set a field separator
IFS=-

# Expand your variable into positional parameters
set - $s

# Drop the first two fields
shift 2

# Drop additional fields until one that starts with a digit
while ! expr "$1" : '[0-9]' >/dev/null; do shift; done

# Capture the part of the string that is not digits
y="$1"; while expr "$y" : '[0-9]' >/dev/null; do y="${y##[[:digit:]]}"; done

# Strip off the non-digit part from the original field
x="${1%$y}"

Note that this may fail for a string that looks like aa-bb-123cc45-foo. If you might have additional strings of digits in the "interesting" field, you'll need more code.

If you have a bash shell available, you could do this with a series of bash parameter expansions...

# Strip off the first two "fields"
x="${s#*-}"; x="${x#*-}"
shopt -s extglob
x="${x##+([^[:digit:]])}"

# Identify the part on the right that needs to be stripped
y="${x##+([[:digit:]])}"

# And strip it...
x="${x%$y}"

This is not POSIX compatible because if the requirement for extglob.

Of course, bash offers you many options. Consider this function:

whatdigits() {
  local IFS=- x i
  local -a a
  a=( $1 )

  for ((i=3; i<${#a[@]}; i++)) {
    [[ ${a[$i]} =~ ^([0-9]+) ]] && echo "${BASH_REMATCH[1]}" && return 0
  }

  return 1
}

You can then run commands like:

$ whatdigits "12-ab-cd-45ef-gh"
45
$ whatdigits "$s"
8080

Upvotes: 0

stack0114106
stack0114106

Reputation: 8711

Try this Perl solution

$ data="prod2-03_dl-httpd-prod-8080_access_referer_log.20181111-050000"

$ perl -ne ' /.+?\-(\d+).+?\-(\d+).*/g and print $2 ' <<< "$data"
8080

or

$ echo "$data" | perl -ne ' /.+?\-(\d+).+?\-(\d+).*/g and print $2 '
8080

Upvotes: 0

Micha Wiedenmann
Micha Wiedenmann

Reputation: 20853

There is no need to resort to sed, BASH supports regular expressions:

$ A=prod2-03_dl-httpd-prod-8080_access_referer_log.20181111-050000
$ [[ $A =~ ([^-]*-){2}[^[:digit:]]+([[:digit:]]+) ]] && echo "${BASH_REMATCH[2]}"
8080

Upvotes: 1

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