zcat
Archives
Usage
zcat <file.gz>Streams what is inside a .gz to stdout without ever unpacking it to disk, which is how you grep a rotated log in place; `-f` lets plain uncompressed files through in the same pass, and bzip2, xz and zstd have their own bzcat, xzcat and zstdcat.
Common flags
| Flag | Meaning |
|---|---|
| <file.gz> | Print the contents to stdout, leaving the file compressed. |
| -f | Also pass through files that are not compressed at all. |
| zgrep / zless | The same idea for searching and paging a .gz file. |
| bzcat / xzcat / zstdcat | The equivalents for bzip2, xz and zstd. |
Examples
zcat access.log.gz | grep " 500 "Search a rotated log without unpacking it.
zcat -f app.log app.log.1.gz | tail -100Read across compressed and plain logs in one pass.
Bundling and compressing are separate jobs: tar bundles, gzip shrinks, and .tar.gz is both.
How to read this
- Square brackets [ ] mark a part you may leave out.
- An ellipsis … means you can list more than one.
- Flags are case-sensitive — in some commands -r and -R do different things.
Questions
Q. What does zcat do?
Streams what is inside a .gz to stdout without ever unpacking it to disk, which is how you grep a rotated log in place; `-f` lets plain uncompressed files through in the same pass, and bzip2, xz and zstd have their own bzcat, xzcat and zstdcat.
Q. How do I type it?
zcat <file.gz> — square brackets mark the parts you can leave out.
Q. How many flags are worth knowing?
4 are listed here; the full set is in man zcat. This command sits under Archives.
Related commands
man page: man zcat