Transportable Cat?

[WesselAtWork]

Is there some kind of command that works on both DOS and Linux that can extract the contents of a file and put it into stdout?
cat is a no go as it's not available on DOS.

I needed to do some logic that boils down to: "If file exists, use it's contents, else, invoke one-ish time command to get value"

Minimal mock

Breaks on DOS.

some-task:
  desc: "Mock Minimal Cat"
  vars:
    MY_VALUE:
      sh: 'cat backup.txt || echo "my one-ish time command"'
  cmd: 
    - 'echo "{{.MY_VALUE}}" > backup.txt '
    - 'echo "{{.MY_VALUE}} -- command failure sim" && false' 
    - 'rm -f backup.txt'

[WesselAtWork]

echo $(<)

echo "$(<backup.txt)"

---

Figured it out!

Becuase go-task uses mvdan/sh as it's command runner I just needed to use bashy contructs to get the file contents.

My original problem

Sadly I cant do echo "$(<backup.txt)" || echo "works", the bashism fails in the interpreter [ :( ]

Needed to add a test:

some-task:
  desc: "Mock Minimal Cat"
  vars:
    MY_VALUE:
      sh: '[ -f backup.txt ] && echo "$(<backup.txt)" || echo "my one-ish time command"'
  cmd: 
    - 'echo "{{.MY_VALUE}}" > backup.txt '
    - 'echo "{{.MY_VALUE}} -- command failure sim" && false' 
    - 'rm -f backup.txt'

[WesselAtWork]

Painfully there is no transportable rm [ >:( ]

I'll keep this here for if to need to read a file, but I'm still figuring out if it's even possible to delete in the first place

[WesselAtWork]

Not as elegant as the $(<) solution but will get you there:

      - cmd: rm backup.txt
        ignore_error: true
      - cmd: cmd /c del backup.txt
        platform: ["windows"]

rm should work on everything else

[WesselAtWork]

As of August 2025 we have fake gnu utils in DOS!
https://taskfile.dev/blog/windows-core-utils
#2360

---

You can now just use it directly on DOS

some-task:
    desc: "Mock Minimal Cat"
    vars:
      MY_VALUE:
        sh: '[ -f backup.txt ] && cat backup.txt || echo "my one-ish time command"'
    cmds:
      - cmd: 'echo "{{.MY_VALUE}}" > backup.txt '
      - cmd: 'cat backup.txt'
      - cmd: 'rm -f backup.txt'

You still need to do the test [ -f backup.txt ] because fake cat fails fatally when it can't access the file.
See #2466