How to save session cookies in wget

Authenticated downloads often depend on a short-lived web session instead of a static token or HTTP basic-auth credential. Saving session cookies from wget keeps a scripted download sequence inside the same server-side login context and avoids rebuilding the login flow for every request in a batch job.

GNU wget writes cookies with --save-cookies, reloads them with --load-cookies, and only preserves session cookies when --keep-session-cookies is also present. Those saved values use the Netscape cookie-jar format, and session rows are written with an expiry of 0 so later wget runs can treat them as part of the same browser-style session.

Cookie jars are credentials in practice. Keep them in a restricted directory, expect the site to rotate or invalidate them, and delete them when the automation step is complete so the replay window is as small as possible.

Steps to save session cookies in wget:

Create and enter an isolated working directory for the cookie jar and the downloaded content.
```
$ mkdir -p "$HOME/wget-session"
$ cd "$HOME/wget-session"
```
Keeping the jar in a dedicated directory makes cleanup and permission review straightforward once the session is no longer needed.

Send the login or cookie-setting request with both --save-cookies and --keep-session-cookies enabled.

$ wget --save-cookies session-cookies.txt \
  --keep-session-cookies \
  --output-document=/dev/null \
  'https://httpbin.org/cookies/set?sessionid=codexdemo123'
--2026-03-27 06:56:46--  https://httpbin.org/cookies/set?sessionid=codexdemo123
Resolving httpbin.org (httpbin.org)... 44.221.213.41, 54.146.128.0, 44.196.185.120, ...
Connecting to httpbin.org (httpbin.org)|44.221.213.41|:443... connected.
HTTP request sent, awaiting response... 302 FOUND
Location: /cookies [following]
--2026-03-27 06:56:47--  https://httpbin.org/cookies
Reusing existing connection to httpbin.org:443.
HTTP request sent, awaiting response... 200 OK
Length: 55 [application/json]
Saving to: '/dev/null'

     0K                                                       100% 13.1M=0s

2026-03-27 06:56:47 (13.1 MB/s) - '/dev/null' saved [55/55]

Sites that require a form login use the same cookie flow; replace the URL with the real login request and add the matching POST body when needed.

Restrict the cookie jar permissions before reusing the saved session.
```
$ chmod 600 session-cookies.txt
$ ls -l session-cookies.txt
-rw-------  1 user user 135 Mar 27 06:56 session-cookies.txt
```
Anyone who can read the jar can usually replay the authenticated session until the site expires or revokes it.
Inspect the saved jar and confirm the session cookie was written with an expiry of 0.
```
$ sed -n '1,8p' session-cookies.txt
# HTTP Cookie File
# Generated by Wget on 2026-03-27 06:52:47.
# Edit at your own risk.

httpbin.org	FALSE	/	FALSE	0	sessionid	codexdemo123
```
The 0 expiry is how wget marks a saved session cookie when --keep-session-cookies is enabled.
Reload the jar on the next request and confirm the remote service sees the same session value.
```
$ wget --load-cookies session-cookies.txt -qO- https://httpbin.org/cookies
{
  "cookies": {
    "sessionid": "codexdemo123"
  }
}
```
Use a protected page, account dashboard, or echo endpoint that exposes the session state so a redirected login page is not mistaken for success.
Combine --load-cookies and --save-cookies on later requests when the site refreshes the session during the workflow.
```
$ wget --load-cookies session-cookies.txt \
  --save-cookies session-cookies.txt \
  --keep-session-cookies \
  -qO- https://httpbin.org/cookies
{
  "cookies": {
    "sessionid": "codexdemo123"
  }
}
```
Rewriting the same jar lets one automation run carry forward refreshed cookie values without starting over from the login step.
Remove the session jar after the job finishes.
```
$ rm -f session-cookies.txt
```
Delete the jar only after the final authenticated request is complete so the workflow does not lose the session mid-run.