From: Felix Kästner Date: Mon, 5 Jul 2021 20:30:11 +0000 (+0000) Subject: add content X-Git-Url: https://fpunktk.de/gitweb/?p=travelrc.git;a=commitdiff_plain;h=2ae6bb879bdb4d7ac2900e4d9af009e4fe6abbcc add content --- diff --git a/README.md b/README.md index 188145f..d674225 100644 --- a/README.md +++ b/README.md @@ -1,3 +1,185 @@ -# travelrc +# travelrc – take your rc-files with you when using ssh or su -take your rc-files with you when using ssh or su \ No newline at end of file + ## What is the problem? + +Over the years, I massively configure commandline tools that I regularly use, like bash, vim, screen an so on. +I created aliases, a custom prompt, special keybindings and commands. +It fits my workflow very well. +But every time I switch to another system (ssh to a local VM, or cloud-VM, or a docker container; changing to root) none of these settings work anymore and I'm annoyed. + +## How can it be solved? + +I put my rc-files in a git repo and cloned it on systems that I use regularly. +It works, I just have to pull my latest changes a lot. +But it does not work on temporal systems or on systems where I do not want to clone (or can't clone) all my rc-files. +The requirements that I came up with for traveling with my rc-files are like this: + +* only save travelled rc-files temporarily +* it's okay to travel with just the most important rc-files +* do not interfere with already existing rc-files (especially for shared accounts like root) +* use it with ssh, su (changing to root or another user on the same machine), docker, and probably more +* do not add too much steps in the process (no rollout via ansible, no scp then ssh), keep it ephemeral + +## How did I solve it? + +I searched the internet for solutions to my problem, found something (https://github.com/IngoMeyer441/sshrc) and extended and (in my opinion) improved it. + +The basic idea is to minify (remove comments), compress and tar the rc-files, +convert this archive to a (long) string (base64 encode), +and add this string and commands to decompress and extract it as a command to ssh (or su/docker). + +My solution requires some steps which I'll outline here. +It can be used as is, but it can also act as an inspiration for other solutions. + +* create a directory (the name of the directory is used once in the ```minify-trc``` function below) and symlink (or copy) the rc-files, that should travel with you, into it + +``` +mkdir $HOME/.travelrc +ln -s -t $HOME/.travelrc $HOME/{.bashrc,.inputrc,.vimrc,.screenrc,.tmux.conf} +``` + +* add a directory with executables that should be available in the travelled session + +``` +mkdir $HOME/.travelrc/trcbin +echo '#!/bin/bash +bash --rcfile "$TBASHRC"' > $HOME/.travelrc/trcbin/trcbash +chmod +x $HOME/.travelrc/trcbin/trcbash +``` + +* add helper functions to your ```.bashrc``` + +``` +minify-trc() { + # this function copies the trc files to a tempdir and minifies them, it returns the tempdirname on stdout + local trcdir="${TRAVELRCDIR:-$HOME/.travelrc}" # use the travelled rc dir if already travelled + [ -f "$trcdir/.bashrc" ] || { echo "file .bashrc inside trcdir \"$trcdir\" does not exist" >&2; return 1; } + # remove all comments from the files to decrease size, has to be done carefully (comment characters can be inside quotes or other commands) + echo -n "minifying trcdir... " >&2 + local trc_min_dir="$(mktemp --directory "/tmp/.trc.min.XXXXXX")" + cp --dereference --recursive --target-directory="$trc_min_dir" "$trcdir/"* + [ -f "$trc_min_dir/.vimrc" ] && sed --in-place -e 's/^ *".*$//' -e 's/ \+" .*$//' "$trc_min_dir/.vimrc" # special minifyer for vimrc + find "$trc_min_dir/" -type f -exec sed --in-place -e 's/^ *#[^!].*$//' -e 's/ \+# .*$//' '{}' '+' # minify all files as if they were shell scripts + echo "$trc_min_dir" +} + +trccmd() { + # echo all the commands to travel with rc files, arguments act as additional arguments to tar + local trc_min_dir="$(minify-trc)" + echo -n "packing trcdir... " >&2 + local trcvar="$(tar --create --file=- "$@" --directory="$trc_min_dir" --dereference ./ | base64 --wrap=0)" # this writes the compressed contents of $trc_min_dir base64-encoded to $trcvar + rm -rf "$trc_min_dir" # delete the temporal directory generated by minify-trc + echo "to ${#trcvar} bytes... " >&2 + [ ${#trcvar} -lt 65536 ] || { echo "content of trcdir \"$trcdir\" is too big, even after minifying" >&2; return 1; } + # export $TRAVELRCDIR and create this directory, it could also be created in /tmp + echo ' +export TRAVELRCDIR=$HOME/.travelrc.travelled +readonly TRAVELRCDIR +mkdir --parents $TRAVELRCDIR +' + # SSH_TTY should still be set to figure out whether this is a ssh session + [ -z "$SSH_TTY" ] || echo "export SSH_TTY=$SSH_TTY" + # decompress the files saved to $trcvar; start a bash with the travelled rc-file; only remove $TRAVELRCDIR if there is no screen or tmux session (which can still use the files); last command is true so that the returncode is always 0 + # TODO: is it save to always remove $TRAVELRCDIR because it will be recreated on the next connection? + echo ' +echo '"$trcvar"' | base64 --decode | tar --file=- --extract '"$@"' --touch --directory=$TRAVELRCDIR +chmod --quiet --recursive go= $TRAVELRCDIR +bash --rcfile $TRAVELRCDIR/.bashrc +screen -ls 1>/dev/null 2>&1 || tmux has-session 1>/dev/null 2>&1 || rm -rf $TRAVELRCDIR +true +' +} +``` + +* add functions to your ```.bashrc``` that enable travelling with the rc files via ssh, su, and docker + * I prepended a „t“ to each of these commands, so when I type ```ssh host``` and realize that my rc-files are missing, I can disconnect, prepend a „t“ tho the previous command (to get ```tssh host```) and everything is better :-) + * this code has to be added after the helper functions mentioned above + +``` +tssh() { + # use -t to force the allocation of a terminal + ssh -t "$@" "$(trccmd --xz)" +} +complete -F _ssh tssh # this is the same as for ssh; function _ssh might not exist when this is called, but will be created automagically when requesting completion for ssh + +tdocker() { + local dcmd="$1" + shift + # some docker images don't come with --xz support, so --gzip is used + docker "$dcmd" --interactive --tty "$@" bash -c "$(trccmd --gzip)" +} +# TODO: add completion + +tsu() { # travel substitude user + local next_user="${1:-root}" + local tsu_cmd="$(mktemp "/tmp/.tsu-cmd.XXXXXX")" + # create a script as tsu_cmd, which should always return 0 to be able to tell whether tsu was successful + trccmd --gzip > "$tsu_cmd" + chmod --quiet ugo=rx "$tsu_cmd" + # try several ways to change the user and execute the tsu_cmd + local tsu_done="false" + if type -P sudo &>/dev/null; then + # the groups test might not be very accurate, but it is quiet; sudo is usually allowed for user vagrant + # the sudo test is accurate, but creates log messages, which might not be desired, especially when sudo is not allowed + if groups | \grep --quiet -e "sudo" -e "admin" -e "wheel" || [ "$USER" = "vagrant" ] #\ + #|| \sudo -nv &>/dev/null || \sudo -nv 2>&1 | \grep --quiet '^sudo:' # sudo is allowed with or without password + then + echo "trying sudo, enter your password:" + # 'sudo -u' seems better than 'sudo su' because the latter displayed problems with IOCTL (I/O-Control) + sudo -u "$next_user" "$tsu_cmd" && tsu_done="true" + #sudo su "$next_user" --command "$tsu_cmd" && tsu_done="true" + else + read -p "sudo might not be allowed for you ($USER), try anyway? [y/N] " try_sudo_anyway + [ "y" = "$try_sudo_anyway" ] && sudo -u "$next_user" "$tsu_cmd" && tsu_done="true" + fi + if ! "$tsu_done" && [ "$next_user" != "root" ]; then + echo "trying su 'root' to call sudo '$next_user', enter root's password:" + su "root" --command "sudo -u $next_user $tsu_cmd" && tsu_done="true" + fi + fi + if ! "$tsu_done"; then + echo "trying su '$next_user', enter $next_user's password:" + su "$next_user" --command "$tsu_cmd" && tsu_done="true" + fi + if ! "$tsu_done"; then + echo "trying su 'root' --command su '$next_user', enter root's password:" + su "root" --command "su $next_user --command '$tsu_cmd'" && tsu_done="true" + fi + $tsu_done || echo "sorry, tsu did not work in this case :-(" + rm --force "$tsu_cmd" +} +complete -A user tsu # complete usernames +``` + +* add code to your ```.bashrc``` (the one that will travel) to detect whether this is a „travelled rc session“ and make some configurations, i.e. make screen and vim use the travelled rc-files, and add the „trcbin“ directory to PATH + * I have this at the beginning of my ```.bashrc```, but _after_ defaults for ```EDITOR``` and ```INPUTRC``` have been set + +``` +if [ -n "$TRAVELRCDIR" ]; then # this is a travelled rc session + [ -f "$TRAVELRCDIR/.bashrc" ] && export TBASHRC="$TRAVELRCDIR/.bashrc" + [ -f "$TRAVELRCDIR/.inputrc" ] && export INPUTRC="$TRAVELRCDIR/.inputrc" + [ -f "$TRAVELRCDIR/.screenrc" ] && type -P screen &>/dev/null && alias screen="$(type -P screen) -c $TRAVELRCDIR/.screenrc -s trcbash" + [ -f "$TRAVELRCDIR/.tmux.conf" ] && type -P tmux &>/dev/null && alias ttmux="$(type -P tmux) -f $TRAVELRCDIR/.tmux.conf new-session 'trcbash'" # this alias does not work properly when named "tmux" (it fucked up other calls of tmux) + if [ -f "$TRAVELRCDIR/.vimrc" ] && type -P vim &>/dev/null; then + export EDITOR="$(type -P vim) -u $TRAVELRCDIR/.vimrc" + alias vim="$EDITOR" + fi + [ -d "$TRAVELRCDIR/trcbin" ] && export PATH="$TRAVELRCDIR/trcbin:$PATH" # add (prepend) trcbin to PATH +fi +``` + +## FAQ + +* Can it fix more problems? + * yes, you can add more executables to PATH + * I had to execute scripts that unnecessarily used ```clear```, which meant that I was not able to scroll up anymore, so I added a script to the ```trcbin``` directory with the name ```clear```, but which did not do a real clear → problem solved (for me) +* Can it be used with zsh? + * most likely yes, just replace bash with zsh, but zsh might not be installed on the destination-system and then you're screwed; perhaps bash works with most of the zsh configurations, I can't tell +* Is it very efficient? + * probably not :-( + * I've tried to make it efficient, but I think in some cases it starts much more shells then necessary (i.e. ```trcbash``` in the ```trcbin``` directory) + * it might slow down ssh connections a few seconds, but for me having my rc-files with me outweighs this downside +* Does it work with tmux? + * not very well (see the ttmux alias above), but when tmux is started (or a new window is created), just type ```trcbash``` and you'll get a proper bash ;-) +* Is this project finished? + * I've been using it for around a year now and am still improving if necessary