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Split Large Files and Rejoin Them with split and cat

split cuts a file into size-bounded chunks; cat concatenated in order rebuilds the original byte-for-byte.

LinuxcatarchivesplitLow risk
Run `split -b 1G bigfile.iso bigfile.part.` to split into 1 GB chunks, then `cat bigfile.part.* > bigfile.iso` to rejoin.

01Command

Command
$ split -b 1G bigfile.iso bigfile.part. && cat bigfile.part.* > bigfile.iso

02What it does

For text, split by lines with `-l 1000000`; add `-d` for numeric suffixes (part.00, part.01) that sort naturally across systems. The rejoin order matters: `cat bigfile.part.*` works because the glob sorts alphabetically and split's default aa/ab/ac suffixes are ordered — switching to `-d` keeps that true. Verify a rebuilt binary with `cmp` or sha256sum against the original.

03Risk

RiskLow risk
Requirementscoreutils (default)

04Undo

✓No undo needed — this command does not change persistent state.

05Sources

  • split(1) - Linux manual page
    Ubuntu Manpages · technical · 2026-09-17
    Evidence: split splits a file into fixed-size pieces with -b (bytes) or -l (lines), -d for numeric suffixes, and -n for a number of chunks; cat concatenates them back.

Last verified: 2026-09-17 · Category: Files & Folders