Bash Scripting – Encode File Content and Echo as One Line

bashecho

I am trying to echo the content of key and certificate files encoded with base64 so that I can then copy the output into other places.

I found this thread: Redirecting the content of a file to the command echo? which shows how to echo the file content and also found ways to keep the newline characters for encoding. However when I add the | base64 this breaks the output into multiple lines, and trying to add a second echo just replaces the newlines with white spaces.

$ echo "$(cat test.key)" | base64
LS0tLS1CRUdJTiBQUklWQVRFIEtFWS0tLS0tCk1JSUpRZ0lCQURBTkJna3Foa2lHOXcwQkFRRUZB
QVNDQ1N3d2dna29BZ0VBQW9JQ0FRRFF4Tkh0aHZvcEp1Z0EKOHBsSUNUUU1pOGMwMzRERlR6Z1E5
ME5tcE5zN2hRczNQZ0QwU2JuSFcyVGxqTS9oM1F1QVE0Q1dqaHRiV1ZUbgpSREcveGxWRFBESVVV
MzB1UHJnK0N6dlhOUkhzQkE9PQotLS0tLUVORCBQUklWQVRFIEtFWS0tLS0tCg==

$ echo $(echo "$(cat test.key)" | base64)
LS0tLS1CRUdJTiBQUklWQVRFIEtFWS0tLS0tCk1JSUpRZ0lCQURBTkJna3Foa2lHOXcwQkFRRUZB QVNDQ1N3d2dna29BZ0VBQW9JQ0FRRFF4Tkh0aHZvcEp1Z0EKOHBsSUNUUU1pOGMwMzRERlR6Z1E5 ME5tcE5zN2hRczNQZ0QwU2JuSFcyVGxqTS9oM1F1QVE0Q1dqaHRiV1ZUbgpSREcveGxWRFBESVVV MzB1UHJnK0N6dlhOUkhzQkE9PQotLS0tLUVORCBQUklWQVRFIEtFWS0tLS0tCg==

The desired output would be:

LS0tLS1CRUdJTiBQUklWQVRFIEtFWS0tLS0tCk1JSUpRZ0lCQURBTkJna3Foa2lHOXcwQkFRRUZBQVNDQ1N3d2dna29BZ0VBQW9JQ0FRRFF4Tkh0aHZvcEp1Z0EKOHBsSUNUUU1pOGMwMzRERlR6Z1E5ME5tcE5zN2hRczNQZ0QwU2JuSFcyVGxqTS9oM1F1QVE0Q1dqaHRiV1ZUbgpSREcveGxWRFBESVVVMzB1UHJnK0N6dlhOUkhzQkE9PQotLS0tLUVORCBQUklWQVRFIEtFWS0tLS0tCg==

How can I achieve this output?

Best Answer

Use the -w option (line wrapping) of base64 like this:

... | base64 -w 0

A value of 0 will disable line wrapping.

Related Solutions

Bash – How to decode a list of base64-encoded file names

Just add the base64 encoding of newline (Cg==) after each file name and pipe the whole thing to base64 -d:

find . -name "*_*" -printf "%f\n" |
  sed -n 's/_....-..-..\.pdf$/Cg==/p' |
  base64 -d

With your approach, that would have to be something like:

find . -name "*_*" -printf "%f\0" |
  sed -zn 's/_....-..-..\.pdf$//p' |
  xargs -r0 sh -c '
    for i do
      echo "$i" | base64 -d
    done' sh

as you need a shell to create those pipelines. But that would mean running several commands per file which would be quite inefficient.

Bash Scripting – Echo New Line and String Beginning with \t

echo -e "\\t"

passes \t to echo because backslash is special inside double-quotes in bash. It serves as an escaping (quoting) operator. In \\, it escapes itself.

You can either do:

echo -e "\\\\t"

for echo to be passed \\t (echo -e "\\\t" would also do), or you could use single quotes within which \ is not special:

echo -e '\t'

Now, echo is a very unportable command. Even in bash, its behaviour can depend on the environment. I'd would advise to avoid it and use printf instead, with which you can do:

printf 'test\n\\test\n'

Or even decide which parts undergo those escape sequence expansions:

printf 'test\n%s\n' '\test'

Or:

printf '%b%s\n' 'test\n' '\test'

%b understands the same escape sequences as echo (some echos), while the first argument to printf, the format, also understands sequences, but in a slightly different way than echo (more like what is done in other languages). In any case \n is understood by both.

Best Answer

Related Solutions

Bash – How to decode a list of base64-encoded file names

Bash Scripting – Echo New Line and String Beginning with \t

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