Reference

Install and uninstall packages from SSC, including from date-based snapshots of an SSC mirror. Web rendering of the Stata help file (help ssc2).

Syntax

Describe a specified package at SSC mirror

ssc2 describe { pkgname | letter } [, saving(filename[, replace]) date(datespec) from(url)]

Install a specified package from SSC mirror

ssc2 install pkgname [, all replace update replaceall date(datespec) from(url)]

Type a specific file stored at SSC mirror

ssc2 type filename [, asis date(datespec) from(url)]

Copy a specific file from SSC mirror to your computer

ssc2 copy filename [, plus personal replace public binary date(datespec) from(url)]

where letter in ssc2 describe is a-z or _, and datespec is a date in YYYY-MM-DD format or the word latest.

Command overview

Subcommands that accept date() and from(), and therefore can act on a snapshot:

ssc2 install pkgname installs the specified package, from a dated snapshot when date() is given. See Options for selecting a snapshot and Options for use with ssc2 install.

ssc2 describe pkgname describes, but does not install, the specified package as it stood in the selected snapshot. Give a single letter, a-z or _, instead of a package name to list all packages starting with that letter in that snapshot.

ssc2 type filename and ssc2 copy filename display and copy an individual file from the selected snapshot. ssc2 cat and ssc2 cp are synonyms.

Subcommands specific to ssc2:

ssc2 snapshots reports the snapshot coverage of the mirror and how to point ssc2 at a different one.

ssc2 versions pkgname is not yet implemented. It will list the versions of a package available across snapshots.

Subcommands passed through to ssc unchanged: ssc2 new (whatsnew), ssc2 hot (whatshot), and ssc2 uninstall. Their options are documented in ssc.

Options for selecting a snapshot (describe, install, type, copy)

date(datespec) selects the snapshot of the SSC archive as of the specified date. datespec is either a date in YYYY-MM-DD format (for example, date(2022-01-07)) or latest, which uses the most recently mirrored state of the archive. If no snapshot exists for the specified date, an error message points to the list of available snapshot dates.

from(url) specifies the base URL of the snapshot mirror. If from() is not specified, the URL is taken from the Stata global SSC2_MIRROR if that is set; otherwise from the environment variable SSC2_MIRROR if that is set; otherwise the built-in default https://raw.githubusercontent.com/ssc-ng/archive is used. The overrides exist because the mirror may move to a different host; they also let you point at your own clone, which must use the same layout (url/ref/fmwww.bc.edu/repec/bocode/). The analogous SSC2_MIRROR_API global or environment variable overrides the API endpoint used only for diagnosing failed snapshot lookups.

Options for use with ssc2 install

When a snapshot is requested with date() or from(), ssc2 install compares the requested snapshot with any installed copy of the same package, using the snapshot date recorded in the installed copy’s source; a copy installed from SSC directly carries no snapshot date and cannot be compared. Because repeated dated installs would otherwise accumulate multiple entries in the ado directory (each snapshot is a distinct source URL, and ado uninstall would then report that more than one package matches), each of the three options below removes the superseded copies before installing.

replace reinstalls the same snapshot. If an installed copy is from a different snapshot, or has no snapshot date, the install is refused and the message points to update and replaceall. Without date() or from(), replace has its usual ssc meaning (see below), except that a snapshot-installed copy of the package is retired first so the package remains singly tracked.

update (only with date() or from()) installs the requested snapshot only if it is newer than every installed copy of the package. If the installed copy is the same age or newer, nothing is done.

replaceall (only with date() or from()) replaces any installed version of the package without comparing versions; this is the option to use for downgrading, and the only applicable one with date(latest).

If none of the three is specified and any file of the package already exists, nothing is downloaded or installed, exactly as with ssc.

Options inherited from ssc

The following options behave exactly as they do in ssc, and are documented in ssc: all with ssc2 install; replace with ssc2 install when no snapshot is requested (see above for the snapshot case); saving() with ssc2 describe and ssc2 new; type with ssc2 new; n() and author() with ssc2 hot; asis with ssc2 type; and plus, personal, replace, public, and binary with ssc2 copy.

Keeping packages up to date

ado update checks each installed package against the source it was installed from and updates those that have changed. Packages installed by ssc2 from a dated snapshot record that snapshot’s URL as their source, and a snapshot never changes, so ado update leaves them as they are: a pinned package stays pinned. Packages installed without date() come from SSC itself and are updated normally.

To move a pinned package to a different snapshot, install it again with the new date() and update (to move forward only) or replaceall (to move in either direction). To return a package to ordinary SSC tracking, install it without date(), using replace.

Use ssc2 uninstall (a synonym for ado uninstall) to remove a package, however it was installed.

Examples

Describe the package oaxaca

. ssc2 describe oaxaca

This passes through the request to ssc, describing the package on SSC.

Describe the package oaxaca as of a specific date

. ssc2 describe oaxaca, date(2022-01-07)

Install package oaxaca as of a specific date

. ssc2 install oaxaca, date(2022-01-07)

Uninstall previously installed package oaxaca

. ssc2 uninstall oaxaca

This uninstalls the installed copy of oaxaca, regardless of how it was installed.

Generated automatically from sthlp/ssc2.sthlp on 2026-10-19. The in-Stata help file is the authoritative version.