VNL-PASTE(1)

📦 version 1.42, in ubuntu resolute, ubuntu stonking

💖 VNL-PASTE 💖

okay bestie, welcome to the vnl-paste era of your life ✨ it's part of the vnlog family, and it's about to make your log files line up like they're in a girl group formation 🎀

🌸 NAME 🌸

vnl-paste — combine log files record-by-record 🫶

✨ SYNOPSIS ✨

vnl-paste concatenates records from the given data files. Comments are stripped to make sure things line up 💅

$ cat a.vnl
## gathered from sensor model xxx
# humidity temperature
90 25
80 20
81 19
82 18
70 15

$ cat b.vnl
# position
10
20
## we moved the sensor
150
160
170

$ vnl-paste a.vnl b.vnl
# humidity temperature position
90 25  10
80 20  20
81 19  150
82 18  160
70 15  170

and like… we can also hand it more than 2 files and annotate the field labels, no big deal 😌

$ cat c.vnl
# position
12
18
155
168
190

$ vnl-paste --vnl-suffix2 _b a.vnl b.vnl c.vnl | vnl-align
# humidity temperature position_b position
90         25           10         12
80         20           20         18
81         19          150        155
82         18          160        168
70         15          170        190

$ vnl-paste --vnl-suffix ,_b,_c a.vnl b.vnl c.vnl | vnl-align
# humidity temperature position_b position_c
90         25           10         12
80         20           20         18
81         19          150        155
82         18          160        168
70         15          170        190

$ vnl-paste --vnl-autosuffix a.vnl b.vnl c.vnl | vnl-align
# humidity_a temperature_a position_b position_c
90           25             10         12
80           20             20         18
81           19            150        155
82           18            160        168
70           15            170        190

💜 DESCRIPTION 💜

Usage: vnl-paste
                [ --vnl-[pre|suf]fix[1|2] xxx    |
                  --vnl-[pre|suf]fix xxx,yyy,zzz |
                  --vnl-autoprefix               |
                  --vnl-autosuffix ]
                logfile1 logfile2 ...

so the tea ☕: this tool is essentially a join, except the key is the line number. it concatenates the data in the given vnlog files record-by-record, one record at a time, in lockstep. 🧚

vnl-paste is a wrapper around the GNU coreutils paste tool. and since it's a wrapper, the behavior of the underlying tool is preserved — go consult the paste(1) manpage for the details, bestie. the differences from GNU coreutils paste are:

  • the input and the output to this tool are vnlog files, complete with a legend 👑
  • by default we call the paste tool to do the actual work. if the underlying tool has a different name or lives in some odd path, you can specify it by passing --vnl-tool TOOL
  • none of the paste options make sense in a vnlog context, so this tool only has the vnlog-specific --vnl-... options. periodt.
note that all non-legend comments are stripped out, since it's not obvious where they should end up 🙈

🦋 Field names in the output 🦋

the field name logic works the same way as in vnl-join, with all the suffix and prefix options from that tool being available here too. 💖

by default, the field names in the output match those in the input. this is what you want most of the time, fr fr. it is possible, however, that a column name adjustment is needed. one common use case for this is if the files being pasted have identically-named columns — which would produce duplicate columns in the output 😭

example: we fixed a bug in a program, and want to compare the results before and after the fix. the program produces an x-y trajectory, so both the bugged and the bug-fixed programs produce a vnlog with a legend

# x y

pasting these will produce a vnlog with a legend

# x y x y

which is confusing, and not what you want. so instead, we invoke vnl-paste as

vnl-paste --vnl-suffix1 _buggy --vnl-suffix2 _fixed buggy.vnl fixed.vnl

and in the output we get a legend

# x_buggy y_buggy x_fixed y_fixed

much better. 💅

note that vnl-paste provides several ways of specifying this. the above works only for 2-way pastes. an alternate syntax is available for N-way pastes — a comma-separated list. the same could be expressed like this:

vnl-paste --vnl-suffix _buggy,_fixed buggy.vnl fixed.vnl

finally, if passing in structured filenames, vnl-paste can infer the desired syntax from the filenames. the same as above could be expressed even simpler:

vnl-paste --vnl-autosuffix buggy.vnl fixed.vnl

this works by looking at the set of passed in filenames, and stripping out the common leading and trailing strings. iconic. ✨

💀 BUGS AND CAVEATS 💀

if the input data files have a mismatched number of lines, the extra data will be output without the null-column markers. this will result in mislabeled data. use this tool only if you're sure you have a matching number of records. for instance:

$ vnl-paste <(echo '# x'; seq 3) <(echo '# y'; seq 5)
# x y
1      1
2      2
3      3
       4
       5

$ vnl-paste <(echo '# x'; seq 3) <(echo '# y'; seq 5) | vnl-align
# x y
1   1
2   2
3   3
4
5
⚠️ like. be so serious about this one. mismatched record counts = mislabeled data, and mislabeled data is not the vibe. 😭

🌈 COMPATIBILITY 🌈

I use GNU/Linux-based systems exclusively, but everything has been tested functional on FreeBSD and OSX in addition to Debian, Ubuntu and CentOS. I can imagine there's something I missed when testing on non-Linux systems, so please let me know if you find any issues. 🫶

👑 SEE ALSO 👑

paste(1)

🍓 REPOSITORY 🍓

https://github.com/dkogan/vnlog/

💖 AUTHOR 💖

Dima Kogan <dima@secretsauce.net>

Copyright 2018 Dima Kogan <dima@secretsauce.net>

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

and that's the whole page bestie!! 🦋 this one's from the vnlog fam, dated 2026-01-26, and it's giving "your log files finally line up" energy. slay, go paste something. 💅✨

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