Question 46763 in Debian Question posted in
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Bash to Grep and Exclude At the Same Time Using Regex – Debian

I want to grep a string from command output but remove a substring at the same time. For instance

String = Active: active (running) since Sat 2022-03-12 20:02:20 PKT; 1h 31min ago

What I want = active (running) since 20:02:20 PKT

Removed

  1. Active:
  2. Sat 2022-03-12
  3. ; 1h 31min ago

To do that I have been using regular expression initially

sudo service sshd status |grep -Po '(?<=Active: )(.*) since (.*);'

active (running) since Mon 2022-03-14 01:06:43 PKT;

Can you tell how can i ignore date as well as last semi-colon ; while keeping the time only and have output exactly like:

active (running) since 01:06:43 PKT

Thanks

Full output of command:

● xrdp.service - xrdp daemon
   Loaded: loaded (/lib/systemd/system/xrdp.service; enabled; vendor preset: enabled)
   Active: active (running) since Mon 2022-03-14 01:06:44 PKT; 3 days ago
     Docs: man:xrdp(8)
           man:xrdp.ini(5)
  Process: 668 ExecStartPre=/bin/sh /usr/share/xrdp/socksetup (code=exited, status=0/SUCCESS)
  Process: 682 ExecStart=/usr/sbin/xrdp $XRDP_OPTIONS (code=exited, status=0/SUCCESS)
 Main PID: 687 (xrdp)
    Tasks: 1 (limit: 4915)
   CGroup: /system.slice/xrdp.service
           └─687 /usr/sbin/xrdp

systemd[1]: Starting xrdp daemon...
xrdp[682]: (682)(-1224841088)[DEBUG] Testing if xrdp can listen on 0.0.0.0 port 3389.
xrdp[682]: (682)(-1224841088)[DEBUG] Closed socket 7 (AF_INET6 :: port 3389)
systemd[1]: xrdp.service: Can't open PID file /run/xrdp/xrdp.pid (yet?) after start: No such file or directory```
Tags:

2

Answers


  1. 0

    You can use

    sed -nE 's/^ *Active: +(.* since ).*([0-9]{2}:[0-9]{2}:[0-9]{2}[^;]*).*/12/p'

    Details:

    • -nE – n suppresses default line output and E enables the POSIX ERE regex syntax
    • ^Active: +(.* since ).*([0-9]{2}:[0-9]{2}:[0-9]{2}[^;]*).* – finds lines matching
      • ^ *Active: + – start of string, zero or more spaces, Active: and one or more spaces
      • (.* since ) – Group 1 (1): any text and then space + since + space
      • .* – any text
      • ([0-9]{2}:[0-9]{2}:[0-9]{2}[^;]*) – two digits, :, two digits, :, two digits, and then any zero or more chars other than ;
      • .* – the rest of the string
    • 12 – concatenated Group 1 and 2 values
    • p – prints the result of the substitution.

    See the online demo:

    #!/bin/bash
s='   Active: active (running) since Sat 2022-03-12 20:02:20 PKT; 1h 31min ago'
sed -nE 's/^ *Active: +(.* since ).*([0-9]{2}:[0-9]{2}:[0-9]{2}[^;]*).*/12/p' <<< "$s"

    Output:

    active (running) since 20:02:20 PKT
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  2. 0

    With your shown samples, please try following awk code. Written and tested in GNU awk. Simple explanation would be, creating a shell variable named val and sending its value to awk then in awk program I am using match function to match regex to get required value.

    val="Active: active (running) since Sat 2022-03-12 20:02:20 PKT; 1h 31min ago"
echo "$val"  | 
awk '
match($0,/^Active:[[:space:]]+active (running)[[:space:]]+.*[0-9]{4}(-[0-9]{2}){2}[[:space:]]+([0-9]{2}:){2}[0-9]{2}[^;]*/){
  val=substr($0,RSTART,RLENGTH)
  sub(/^Active:[[:space:]]+/,"",val)
  sub(/since[[:space:]]+S+s+S+/,"since",val)
  print val
}
'

    Explanation of regex:

    ^Active:[[:space:]]+       ##Matching value starting from Active: followed by space(s).
active (running)         ##matching active followed by a space followed by (running).
[[:space:]]+.*[0-9]{4}     ##Matching 1 or more spaces then using greedy match to match 4 occurrences of digits.
(-[0-9]{2}){2}             ##Matching - followed by 2 digits and this whole combination 2 times.
[[:space:]]+([0-9]{2}:){2} ##Matching space(s) followed by 2 digits followed by colon and this whole combination 2 times.
[0-9]{2}[^;]*              ##Matching 2 digits and everything after it till a semi-colon comes.
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