Make a backup file: Difference between revisions
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Added PicoLisp |
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f.write("this task was solved during a talk about rosettacode at the PyCon China in 2011") |
f.write("this task was solved during a talk about rosettacode at the PyCon China in 2011") |
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f.close() |
f.close() |
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</lang> |
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=={{header|Racket}}== |
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This version keeps unlimited backups, with <tt>*.bak</tt> being the freshest one, <tt>*.bak1</tt> is an older backup, etc. So each backup moves all existing names up. |
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<lang Racket> |
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#lang racket |
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(define (move-to-backup file) |
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(define backup |
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(regexp-replace #rx"^(.*?)(?:\\.bak([0-9]*))?$" file |
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(λ (_ base num) (~a base ".bak" (add1 (if num (string->number num) 0)))))) |
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(eprintf "~s -> ~s\n" file backup) |
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(when (file-exists? backup) (move-to-backup backup)) |
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(rename-file-or-directory file backup) |
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backup) |
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(define (revise path0) |
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(define path (path->string (normalize-path path0))) ; chase symlinks |
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(when (file-exists? path) (copy-file (move-to-backup path) path)) |
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(display-to-file "Another line\n" path #:exists 'append)) |
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(revise "fff") |
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</lang> |
</lang> |
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