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Fix fread clipboard handling on Windows (fixes #1292) #7640

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Fix fread clipboard handling on Windows (fixes #1292) #7640

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546de99
Fix fread clipboard handling on Windows (fixes #1292)
AmanKashyap0807 Feb 9, 2026
c68136d
addressing linting
AmanKashyap0807 Feb 9, 2026
43b8a22
Tweak fread clipboard checks and error handling on Windows
AmanKashyap0807 Feb 17, 2026
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2 changes: 2 additions & 0 deletions NEWS.md
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Expand Up @@ -38,6 +38,8 @@

4. `rowwiseDT()` now provides a helpful error message when a complex object that is not a list (e.g., a function) is provided as a cell value, instructing the user to wrap it in `list()`, [#7219](https://github.com/Rdatatable/data.table/issues/7219). Thanks @kylebutts for the report and @venom1204 for the fix.

5. `fread()` now recognizes Windows clipboard tokens such as `clipboard`, avoiding shell execution failures, [#1292](https://github.com/Rdatatable/data.table/issues/1292). Thanks @mbacou for the report and @AmanKashyap0807 for the fix.

### Notes

1. {data.table} now depends on R 3.5.0 (2018).
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15 changes: 15 additions & 0 deletions R/fread.R
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Expand Up @@ -63,6 +63,21 @@ yaml=FALSE, tmpdir=tempdir(), tz="UTC")
# input is data itself containing at least one \n or \r
} else if (startsWith(input, " ")) {
stopf("input= contains no \\n or \\r, but starts with a space. Please remove the leading space, or use text=, file= or cmd=")
} else if (grepl("^clipboard(-[0-9]+)?$", tolower(input))) {
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@ben-schwen ben-schwen Feb 16, 2026

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Why do we use grepl here and not simply only read from clipboard when the input is clipboard?

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@AmanKashyap0807 AmanKashyap0807 Feb 17, 2026

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I used regex to consider both 'clipboard' and 'clipboard-128' because original issue #1292 shows the user trying fread('clipboard-128').
However your point is valid, since readClipboard() takes no argument and only read clipboard regardless of any suffix so we can use simple string matching.
but the user who are used to base R's read.delim('clipboard-128') syntax would have to use 'clipboard'. let me know if u want the change I will do it.

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@aitap aitap Feb 18, 2026

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On Windows, R's own clipboard connections can be opened with the description clipboard-<buffer size> in order to set the size limit for writing. It's not needed to read the clipboard. On Unix, X11_primary, X11_secondary, X11_clipboard are also supported. We don't have to support anything except clipboard.

is_windows = identical(.Platform$OS.type, "windows")
if (is_windows) {
# for errors due to permissions, clipboard locked or system errors
clip = tryCatch(utils::readClipboard(),
error = function(e) stopf("Reading clipboard failed on Windows: %s", conditionMessage(e))
)
if (!length(clip) || !any(nzchar(trimws(clip)))) {
stopf("Clipboard is empty.")
}
input = paste(clip, collapse="\n")
} else {
# Note: macOS (pbpaste) and Linux (xclip/xsel) support discussed in #1292
stopf("Clipboard reading is supported on Windows only.")
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@joshhwuu joshhwuu Feb 12, 2026

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i wonder if we must stopf here

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@AmanKashyap0807 AmanKashyap0807 Feb 13, 2026

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I added the explicit error to avoid this potentially confusing behavior on non-Windows systems.
I tested this by commenting out else-stopf() block on Ubuntu 20.04 (WSL). In that case, fread("clipboard") falls through and returns:

> temp <- fread("clipboard")
> print(temp)
Empty data.table (0 rows and 1 cols): clipboard

That said, if preserving the current fallback behavior is preferred for compatibility, I’m happy to remove the stopf() and let the normal control flow continue.

}
} else if (length(grep(' ', input, fixed=TRUE)) && !file.exists(gsub("^file://", "", input))) { # file name or path containing spaces is not a command. file.exists() doesn't understand file:// (#7550)
cmd = input
if (input_has_vars && getOption("datatable.fread.input.cmd.message", TRUE)) {
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8 changes: 8 additions & 0 deletions inst/tests/tests.Rraw
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Expand Up @@ -21515,3 +21515,11 @@ test(2365.1, melt(df_melt, id.vars=1:2), melt(dt_melt, id.vars=1:2))
df_dcast = data.frame(a = c("x", "y"), b = 1:2, v = 3:4)
dt_dcast = data.table(a = c("x", "y"), b = 1:2, v = 3:4)
test(2365.2, dcast(df_dcast, a ~ b, value.var = "v"), dcast(dt_dcast, a ~ b, value.var = "v"))

# Test fread clipboard input on Windows (issue #1292)
if (.Platform$OS.type == "windows") local({
temp <- c("a\tb", "1\t2")
utils::writeClipboard(temp)
on.exit(utils::writeClipboard(""), add = TRUE)
test(2366, fread("clipboard-128"), data.table(a = 1L, b = 2L))
})
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