Cheatsheet: Tar

-c creates a new archive, -x extracts an existing one, -t lists (tests) the contents without extracting, -v is verbose (prints each file name as it's processed), and -f names the archive file and must come last in the flag group since it takes the filename as its argument (e.g. tar -xvf archive.tar, not tar -xvfv). -z adds gzip compression and -j adds bzip2 compression to any of the above.

Append the path(s) after the archive name: tar -xzvf archive.tar.gz path/to/file.txt. To match multiple files with a glob, add --wildcards: tar -xzvf archive.tar.gz --wildcards '*.txt'. Without --wildcards, GNU tar treats the pattern as a literal path, not a shell glob.

GNU tar refuses to append to a compressed archive (tar: Cannot update compressed archives) because gzip/bzip2 streams aren't seekable in a way that supports in-place updates. -r/-u/--delete only work on plain, uncompressed .tar files. To add a file to a compressed archive, extract it, add the file, then recompress, or keep the working archive uncompressed until you're done appending.

Use -C to change directory before adding files, then reference them relative to that directory: tar -czvf archive.tar.gz -C /path/to/directory . creates entries like ./a.txt instead of path/to/directory/a.txt. This is the standard way to avoid absolute-path archives that are annoying to extract elsewhere.

No -- -t only lists the entries tar can read from the archive's header/index; it doesn't checksum file contents against anything. To actually validate an archive against files already on disk, use tar --compare (-d) after extracting, or just try a full tar -xvf into a scratch directory and check the exit code -- a truncated or corrupted archive will fail partway through with a non-zero exit status.