vim commands for bulk incrementing

One common task required as part of Splunk administration was that of managing the serverclass.conf file¹. This file contains a list of servers that belong to a particular class, and all machines of that class receive a particular set of configuration files.

A particularly frequent and some-what annoying task is adding and removing servers from each class list. All servers in that list need be prefixed with whitelist.X, where X is a consecutive number beginning at 0. When servers are added or removed, potentially many entries require updating, and doing this by hand could be error-prone.

Consider the following stanza; 2 machines have been decommissioned (commented out in the file), and 3 new servers added to the end. At this stage, the list would be rejected, as the entries do not begin at 0, there are gaps, and there are duplicates.

[serverClass:windowsserver]
# whitelist.0 = 192.168.0.1 # Decomisioned !
whitelist.1 = 192.168.0.2
whitelist.2 = 192.168.0.3
# whitelist.3 = 192.168.0.4 # Decomisioned !
whitelist.4 = 192.168.0.5
whitelist.5 = 192.168.0.6
whitelist.6 = 192.168.0.7
whitelist.7 = 192.168.0.8
whitelist.8 = 192.168.0.9
whitelist.9 = 192.168.0.10
whitelist.10 = 192.168.0.11
whitelist.10 = 192.168.0.12 # New !
whitelist.10 = 192.168.0.13 # New !
whitelist.10 = 192.168.0.14 # New !

The following commands will renumber and sort the entries nicely.

let i=0
vipoj:'<,'>g/^whitelist.\d\+/s//\='whitelist.'.i/ | let i=i+1
gv:'<,'>!sort

[serverClass:windowsserver]
# whitelist.0 = 192.168.0.1 # Decomisioned !
# whitelist.3 = 192.168.0.4 # Decomisioned !
whitelist.0 = 192.168.0.2
whitelist.1 = 192.168.0.3
whitelist.10 = 192.168.0.13 # New !
whitelist.11 = 192.168.0.14 # New !
whitelist.2 = 192.168.0.5
whitelist.3 = 192.168.0.6
whitelist.4 = 192.168.0.7
whitelist.5 = 192.168.0.8
whitelist.6 = 192.168.0.9
whitelist.7 = 192.168.0.10
whitelist.8 = 192.168.0.11
whitelist.9 = 192.168.0.12 # New !

Explanation

let i=0 {enter}

Create a new variable i, which will be used to count the valid lines.

vip

Visually select the entire paragraph.

oj

o to move the cursor to the other end of the block (the top), and j to move down once, thus skipping the stanza defining line.

:

Prepare to enter a command. vim will automatically insert '<,'>, which means to apply the command to the visual selection.

g/^whitelist.\d\+/

Globally perform a search where the start of the line (^) is followed by whitelist. and at least one number (\d\+). Because we look for whitelist at the begining of the line, the search ignores entries that have been commented out with a hash.

s//\='whitelist.'.i/

Substitute what is found by that search with whitelist. followed by the value of i.

| let i=i+1 {enter}

Increment the value of i.

gv

Repeat the previous visual selection.

:

Prepare to enter a command. Again, vim will automatically insert '<,'>.

:!sort {enter}

Sort the results.

Know a better sort? Please let me know!

References

• Power of G: vim wiki
• Making a list of numbers: vim wiki