Using awk to munge SSH private keys

One of those "because I needed to" answers ....

Having generated a SSH public/private key pair: -

ssh-keygen -t rsa -b 4096 -f /tmp/this_is_a_test -N ""

I wanted to get the private key: -

-----BEGIN OPENSSH PRIVATE KEY-----

b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAACFwAAAAdzc2gtcn

NhAAAAAwEAAQAAAgEAnonsGDeVoFfKyCTzsbof7SL5TWE2a5vWfEHq9fHFNH1WhRYKYm9z

E0SLTnS/uYUT4rs8LfxT4vUYGgoNrtY9BH3V8U624CAsSuKdVc4PQdDt5r7CIZmhqIhEh1

ooMB/Ih0C83j6mU653n5bOBDTf1C8wSBBsZnZoivf0OX/MsHutJZCm1xgMT3NStBPFYhpO

sqqWmMXrOJEBgNR880ECB2SBB29XmmhI2SYlzp3ZvTnGS1FCo4LctGkN7uaMFTMZx4QJgz

v7DCeJuhzOcOSw54F4vJX3JGI9c49CBL7g2bxkzh83UpFZiOzVnwzabzkFIRgfC5eFfcxk

NUxTpCPMpfZX0MAKRMJb59wPSXHPA0pisBEIu9gZOUrDeFmZlwUPuVH4i5wCb/rW2Ynkyf

TKhz8bdC2dCj9/BAUv3axsWNjfgA4J/PvUgZ8yr3+zceRUcG+rzi8AFimR5H4QHMzTP9js

PQ3cQ73OUpK0yl/ER+ibqhfkuz2HlEml8WOEEx5ChzSa+jvxzBBsYS3y4ebGbDbn/hBY2w

L/ZSNeXbfx9iq7docW6U2tVcmuMDN1Voadd1V9cKIWsbJ+/UuPWyLLTw2PjpmyNPQJXPrr

63vXaYskKZOZJ9pFqygZJxe6wepc+XluPkbpf1EmXZKy2wJyJPC/DImCmPDgoT6aslQVCg

sAAAdIY7RrvWO0a70AAAAHc3NoLXJzYQAAAgEAnonsGDeVoFfKyCTzsbof7SL5TWE2a5vW

fEHq9fHFNH1WhRYKYm9zE0SLTnS/uYUT4rs8LfxT4vUYGgoNrtY9BH3V8U624CAsSuKdVc

4PQdDt5r7CIZmhqIhEh1ooMB/Ih0C83j6mU653n5bOBDTf1C8wSBBsZnZoivf0OX/MsHut

JZCm1xgMT3NStBPFYhpOsqqWmMXrOJEBgNR880ECB2SBB29XmmhI2SYlzp3ZvTnGS1FCo4

LctGkN7uaMFTMZx4QJgzv7DCeJuhzOcOSw54F4vJX3JGI9c49CBL7g2bxkzh83UpFZiOzV

nwzabzkFIRgfC5eFfcxkNUxTpCPMpfZX0MAKRMJb59wPSXHPA0pisBEIu9gZOUrDeFmZlw

UPuVH4i5wCb/rW2YnkyfTKhz8bdC2dCj9/BAUv3axsWNjfgA4J/PvUgZ8yr3+zceRUcG+r

zi8AFimR5H4QHMzTP9jsPQ3cQ73OUpK0yl/ER+ibqhfkuz2HlEml8WOEEx5ChzSa+jvxzB

BsYS3y4ebGbDbn/hBY2wL/ZSNeXbfx9iq7docW6U2tVcmuMDN1Voadd1V9cKIWsbJ+/UuP

WyLLTw2PjpmyNPQJXPrr63vXaYskKZOZJ9pFqygZJxe6wepc+XluPkbpf1EmXZKy2wJyJP

C/DImCmPDgoT6aslQVCgsAAAADAQABAAACAES9iKD3eOkNJ9+gJgnpqe4oO/BRNkdySo2W

B0qcieU4c0tBQz9rE3pHPh/Gf1rxWK32gSFvRvAhVVH1CfnE6rAH37vBZYnIaWwO1ileLz

9aV8y06XeoJW/tpckKTmKPZWM/rqSuhW/DNhr8SFeKlYJq84RLmrTSooGfAUXtI9NhzLF9

Bto8kxnf5vwtlmfzACx3ytRy/IqKVRyHBaZziW2rJkcS/+jzTqLY54uu5bomUtRVZ49+Lj

QLWP8894A5p/PaTEWavD+I5S7NTrWkcw/uE2uxmncsIXj5pKZqHRRLm2nEHzitzSSRjA5q

hEu1bYPr8YoVKMxi0xBJB/sjipe8XHPUGskw0XBhklwvGAq6HFMWWNScgNl5wDksb4TPwU

REjcEBsd4CrW1mUNZcaj0lib55TEGcaU9tghmMSmMmjHMF58ZvE3DqaXL+VfjQS1YXiFYX

UBJP4QQl3gDG5ypRCrr69FLahigGCnd/FIWev8BhoFolHft2gb/IJu36JeJ+24V4bHT7oG

2G2LLIoNFe0XL0GvlbyNEKRgtLcAijBhDUZs9UEztH4gmFwAPGisbT+hhlhdC3kpxNARTT

HskggYe//W1ZRX2/pIrw5oRn9g1UZ5A0Syla7Cw0JI0Jgcz5C5YQnMTD58jHOZZeb3zBEZ

XfNrkXPkXEnBkO6dgBAAABAAIePVO0JuF16FYKjdFhKwvGKmgc0+kulT16o9kjFlcj94lx

3MnAMldO8uPEm7IBdQtcF5k6MN3lLjSQF0AN/byJ7tK9+N6o/UQ6VFSR2TkcPc41/J6xH2

oERUXt7pJyygkRjDSotWFnZBzA6LcMiRi5NDjq9wXhNPPbl7Bi1LokZ0Bo6szVfwFSL5F2

cyr20yXqyIX3hIduHfhRrNsMt+DgPHsg45Az3xu1H8eyT2K8YkyMjCDeNmm/PXLv2bQa/f

dszZ+KOa4ORiNj/GnPyqM2vZJwY5wk0RCgCujr9pg7zgzjGxw2BsRxE1/rAASiqnn1iGT3

EPKBFPKViKJ2TtsAAAEBANImJ7PZLFiPwXui9TK/QdhiY9a9+ZE0HOAhVTMvJEMKAtwqak

RpjUVerlnX6KB/F7AX9TV472XTQqJSoHvwhImkWhe5EtHzKjkr/Al8pyQo44yy1Nw0vEfM

ryI7oZddx+tNZDguncyn12H3mxd3hI/qt9Y8rgmcGLsjq3T73OvVDcXueofFj2JEzzcdOj

9ebtfJIrd93xsJXlGr0KdHG0Ozz8uL6nBUpvWgQjp+cyNBkmw9NbsX7zP8h2xmVuY4ofr+

1PvyoKHzY0TdidUKEk6qgskd9wSoxsb7iWEWGpfKeMzIrGRqBfdZI14nCRLQI+vvYX+Z8a

0gFDNNWcpwL8cAAAEBAMEhFQGuhm9SxQ1fFoofYP5Vgx9ftIkCB7VbVhAjqYoKJRxGAhFf

hNSAYlx2bHQAQCMhuufmdQGlBKPcBbVZYkh1uo2224sWrMBPqU0yQlV3UAgtCAd+3jTpWj

KV3OT0cs8pHfj/+Wlt9CldfsOUN1pfXlong1oLejgMKZceyYCpwb/9LjoQupbmC9g4To+X

COgINdHPnpV9sePwoILfJIhWwHCpzw4LSIeuozxWg54J5l0ibMeWfMB/ZgTzFxTmmg1Htr

g5Z7hCKhjrHWwfT5w8oYHuwLpEaKYcZhIq/D2ujWfQGbPp8rbORCj+Ssz8SBOsSk+PpEGG

DivcpWlUW50AAAAOaGF5ZEBEYXZlcy1NQlABAgMEBQ==

-----END OPENSSH PRIVATE KEY-----

into a format suitable to be pasted into a JSON document: -

  "GITHUB_KEY":"-----BEGIN OPENSSH PRIVATE KEY-----

-----END OPENSSH PRIVATE KEY-----\n",

with the \n characters replacing the CR/LF at the end of each line.

Initially I munged the file using TextEdit and search / replace, but that's so "Like a cave person".

Thankfully, there's (always) a better way ...

awk '{printf "%s\\n", $0}' /tmp/this_is_a_test

which returns: -

-----BEGIN OPENSSH PRIVATE KEY-----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\nDivcpWlUW50AAAAOaGF5ZEBEYXZlcy1NQlABAgMEBQ==\n-----END OPENSSH PRIVATE KEY-----\n

Of course, an alternate mechanism ( or many ) exists : -

sed 's/$/\\n/' /tmp/this_is_a_test | tr -d '\n'

Thanks Internet, you rock: -

Replace newlines with literal \n