try

"Do, or do not. There is no try."

We're setting out to change that.

Description

try lets you run a command and inspect its effects before changing your live system. try uses Linux's namespaces (via unshare) and the overlayfs union filesystem.

Getting Started

Dependencies

Has been tested on the following distributions:

Ubuntu 20.04 LTS or later
Debian 12
Centos 9 Stream 5.14.0-325.el9
Arch 6.1.33-1-lts
Alpine 6.1.34-1-lts
Rocky 9 5.14.0-284.11.1.el9_2

Installing

You only need the try script, which you can download by cloning this repository:

$ git clone https://github.com/binpash/try.git

Example Usage

try is a higher-order command, like xargs, exec, nohup, or find. For example, to ungzip file, you can invoke try as follows:

$ try pip3 install libdash
... # output continued below

By default, try will ask you to commit the changes made at the end of its execution.

...
Defaulting to user installation because normal site-packages is not writeable
Collecting libdash
  Downloading libdash-0.3.1-cp310-cp310-manylinux_2_17_x86_64.manylinux2014_x86_64.whl (254 kB)
     ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 254.6/254.6 KB 2.1 MB/s eta 0:00:00
Installing collected packages: libdash
Successfully installed libdash-0.3.1
WARNING: Running pip as the 'root' user can result in broken permissions and conflicting behaviour with the system package manager. It is recommended to use a virtual environment instead: https://pip.pypa.io/warnings/venv

Changes detected in the following files:

/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/ast.py (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/_dash.py (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/__init__.py (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/__pycache__/printer.cpython-310.pyc (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/__pycache__/ast.cpython-310.pyc (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/__pycache__/__init__.cpython-310.pyc (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/__pycache__/parser.cpython-310.pyc (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/__pycache__/_dash.cpython-310.pyc (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/printer.py (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/libdash.so (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/parser.py (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash-0.3.1.dist-info/INSTALLER (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash-0.3.1.dist-info/WHEEL (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash-0.3.1.dist-info/COPYING (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash-0.3.1.dist-info/METADATA (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash-0.3.1.dist-info/REQUESTED (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash-0.3.1.dist-info/RECORD (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash-0.3.1.dist-info/top_level.txt (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.cache/pip/http/f/4/0/e/3/f40e360665950eda8309f6341a788c506584b57c23789004ba8305aa (modified/added)
/tmp/tmp.zHCkY9jtIT/upperdir/home/gliargovas/.cache/pip/http/f/0/0/7/0/f00703c6e1f8a1d0ff85030b4557c24be6d9cdd1430c2700d4af934d (modified/added)

Commit these changes? [y/N] y

Sometimes, you might want to pre-execute a command and commit its result at a later time. Invoking try with the -n flag will return the overlay directory, without committing the result.

$ try -n pip3 install libdash
/tmp/tmp.uCThKq7LBK

Alternatively, you can specify your own overlay directory as follows (note that pip_try_sandbox already exists):

$ try -D pip_try_sandbox pip3 install libdash
$ ls pip_try_sandbox
temproot  upperdir  workdir

As you can see from the output above, try has created an overlay environment in the pip_try_sandbox directory.

Manually inspecting upperdir reveals the changes to the files made inside the overlay during the execution of the previous command with try:

$ ls -lR pip_try_sandbox/upperdir/home/me/.cache
total 40
ls -lR sandbox/upperdir/home/gliargovas/.cache/
sandbox/upperdir/home/gliargovas/.cache/:
total 4
drwxrwxr-x 3 gliargovas gliargovas 4096 Jun 21 00:38 pip

sandbox/upperdir/home/gliargovas/.cache/pip:
total 4
drwxrwxr-x 3 gliargovas gliargovas 4096 Jun 21 00:38 http

sandbox/upperdir/home/gliargovas/.cache/pip/http:
total 4
drwxrwxr-x 4 gliargovas gliargovas 4096 Jun 21 00:38 f

sandbox/upperdir/home/gliargovas/.cache/pip/http/f:
total 8
drwxrwxr-x 3 gliargovas gliargovas 4096 Jun 21 00:38 0
drwxrwxr-x 3 gliargovas gliargovas 4096 Jun 21 00:38 4

sandbox/upperdir/home/gliargovas/.cache/pip/http/f/0:
total 4
drwxrwxr-x 3 gliargovas gliargovas 4096 Jun 21 00:38 0

sandbox/upperdir/home/gliargovas/.cache/pip/http/f/0/0:
total 4
drwxrwxr-x 3 gliargovas gliargovas 4096 Jun 21 00:38 7

sandbox/upperdir/home/gliargovas/.cache/pip/http/f/0/0/7:
total 4
drwxrwxr-x 2 gliargovas gliargovas 4096 Jun 21 00:38 0

sandbox/upperdir/home/gliargovas/.cache/pip/http/f/0/0/7/0:
total 252
-rw------- 1 gliargovas gliargovas 255766 Jun 21 00:38 f00703c6e1f8a1d0ff85030b4557c24be6d9cdd1430c2700d4af934d

sandbox/upperdir/home/gliargovas/.cache/pip/http/f/4:
total 4
drwxrwxr-x 3 gliargovas gliargovas 4096 Jun 21 00:38 0

sandbox/upperdir/home/gliargovas/.cache/pip/http/f/4/0:
total 4
drwxrwxr-x 3 gliargovas gliargovas 4096 Jun 21 00:38 e

sandbox/upperdir/home/gliargovas/.cache/pip/http/f/4/0/e:
total 4
drwxrwxr-x 2 gliargovas gliargovas 4096 Jun 21 00:38 3

sandbox/upperdir/home/gliargovas/.cache/pip/http/f/4/0/e/3:
total 8
-rw------- 1 gliargovas gliargovas 6966 Jun 21 00:38 f40e360665950eda8309f6341a788c506584b57c23789004ba8305aa

You can inspect the changhes made inside a given overlay directory using try:

$ try summary pip_try_sandbox
Changes detected in the following files:

sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/ast.py (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/_dash.py (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/__init__.py (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/__pycache__/printer.cpython-310.pyc (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/__pycache__/ast.cpython-310.pyc (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/__pycache__/__init__.cpython-310.pyc (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/__pycache__/parser.cpython-310.pyc (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/__pycache__/_dash.cpython-310.pyc (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/printer.py (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/libdash.so (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash/parser.py (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash-0.3.1.dist-info/INSTALLER (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash-0.3.1.dist-info/WHEEL (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash-0.3.1.dist-info/COPYING (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash-0.3.1.dist-info/METADATA (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash-0.3.1.dist-info/REQUESTED (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash-0.3.1.dist-info/RECORD (modified/added)
sandbox/upperdir/home/gliargovas/.local/lib/python3.10/site-packages/libdash-0.3.1.dist-info/top_level.txt (modified/added)
sandbox/upperdir/home/gliargovas/.cache/pip/http/f/4/0/e/3/f40e360665950eda8309f6341a788c506584b57c23789004ba8305aa (modified/added)
sandbox/upperdir/home/gliargovas/.cache/pip/http/f/0/0/7/0/f00703c6e1f8a1d0ff85030b4557c24be6d9cdd1430c2700d4af934d (modified/added)

You can also choose to commit the overlay directory contents:

$ try commit pip_try_sandbox

Version History

0.1
- Initial Release

License

This project is licensed under the MIT License - see LICENSE for details.

mccahill / try

try