Using regex in git shell when checking out multiple branches - regex

If I have the following git shell command:
for branch in `git branch -a | grep remotes | grep -v master | sed 's/^.*old\/\(.*\)/\1/g'`; do git branch --track $branch remotes/old/$branch; done
This checks out every single remote branch that exists on the old remote and tracks them using the same name that they have on that remote. However, what if I wanted to slightly change the name that the local branches are checked out has?
What if I have the following remote branches:
release/1.2.1.0
release/1.2.1.1
And I want to check them out under the same parent folder release but I only want the last 3 digits in the version number. So I want my local branches to be:
release/2.1.0
release/2.1.1
I have a simple javascript regex that matches the last 3 digits of the version string: (?:\d\.)(\d.*)
This uses a non-matching group to toss out the first digit followed by the period. The question is, how do I apply that regex to the $branch variable in the git shell bash script above?

First, avoid git branch for loops like this. The correct tool here is git for-each-ref, which is designed to work with scripting languages (git branch is aimed at users and the output format may change in the future, for instance).
To loop over all remote-tracking branches, simply tell for-each-ref to scan the remote-tracking branch namespace. Since you want, more specifically, the remote named old, you can do that very easily by adding /old as well:
git for-each-ref refs/remotes/old
The output here defaults to a triple of objectname objecttype refname. We only care about the refname part (and we can use the :short modifier to drop refs/remotes/ as well, if we like, although we still need to drop the old/ too so we could get away without the modifier). Thus we want to include --format=%(refname:short).
Moving on to bash, bash has built-in regular expression support. Its RE syntax is not quite the same, though, so your existing RE must change. Here is one that probably works for your needs:
bash$ x=1.2.3.4
bash$ [[ $x =~ ([0-9]\.)([0-9.]+) ]] && echo ${BASH_REMATCH[2]}
2.3.4
(There is a bit of subtlety here: using $x changes the way the =~ match applies, which in our case is probably good. As an old school Unix person I generally prefer using expr myself, but in this case I might resort to doing this in Python, which has Perl-style REs, and Javascript/ECMAscript REs are modeled on Perl's. But all that is more or less irrelevant. The most important is that this RE is slightly sub-par as a version number matcher. For instance, it matches strings like "1.3..6". We're safe in that these are invalid branch names—double dots are verboten since they would conflict with the set subtraction syntax in gitrevisions—but it's generally a bit sloppy; with some work we could come up with a tighter expression. It also fails to match revisions starting with two or more digits, but your original RE did as well, so I left that in on purpose.)
Reading in a loop in shell, using -r is generally wise (see Etan Reisner's comment), although in this case we could omit it safely since git controls branch names. I will use it in the example just for form's sake.
Putting these all together:
warn() {
echo "warning: $#" 1>&2
}
# Given an input name release/\d\.(\d|\.)+, make
# a local branch named release/\2 (more or less).
make_local_release_branch() {
local relnum newname
relnum=${1#old/release/}
[[ $relnum =~ ([0-9]\.)([0-9.]+) ]] || {
warn "remote-tracking branch $1 does not conform to name style, ignored"
return
}
newname=release/${BASH_REMATCH[2]}
git rev-parse -q --verify refs/heads/$newname >/dev/null && {
warn "branch $newname already exists, remote-tracking branch $1 ignored"
return
}
git branch --track $branch $1
}
git for-each-ref --format='%(refname:short)' refs/remotes/old |
while read -r rmtbranch; do
case $rmtbranch in
old/release/[0-9]*) make_local_release_branch "$rmtbranch";;
*) warn "skipping remote branch $rmtbranch -- not old/release/[digit]";;
esac
done
(this whole thing is entirely untested).

Related

Effective way of detecting X11 vs Wayland, preferrably with CMake

So I've done some Google searching and this is something that has very little knowledge out there. What would be an effective and foolproof way of detecting whether X11 or Wayland is in use, preferrably at compile-time and with CMake? I need to apply this to a C++ project of mine.
The accepted answer is very inaccurate and dangerous. It just runs loginctl to dump a large list of user-sessions and greps every line with a username or other string that matches the current user's name, which can lead to false positives and multiple matching lines. Calling whoami is also wasteful. So it's harmful, and inaccurate.
Here's a much better way to get the user's session details, by querying your exact username's details and grabbing their 1st session scope's id.
This is a Bash/ZSH-compatible one-liner solution:
if [ "$(loginctl show-session $(loginctl user-status $USER | grep -E -m 1 'session-[0-9]+\.scope' | sed -E 's/^.*?session-([0-9]+)\.scope.*$/\1/') -p Type | grep -ic "wayland")" -ge 1 ]; then
echo "Wayland!"
else
echo "X11"
fi
I really wish that loginctl had a "list all sessions just for a specific user", but it doesn't, so we have to resort to these tricks. At least my trick is a LOT more robust and should always work!
I assume you want to evaluate the display server during compile time, when calling CMake, instead of for every compilation. That's how CMake works and hot it should be used. One downside is, that you have to re-run CMake for every changed display server.
There is currently no default way to detect the running display server. Similar, there is no default code snippet to evaluate the display server by CMake. Just pick one way of detecting the display server that manually works for you or your environment respectively.
Call this code from CMake and store the result in a variable and use it for your C++ code.
For example loginctl show-session $(loginctl | grep $(whoami) | awk '{print $1}') -p Type works for me. The resulting CMake check is
execute_process(
"loginctl show-session $(loginctl | grep $(whoami) | awk '{print $1}') -p Type"
OUTPUT_VARIABLE result_display_server)
if ("${resulting_display_server}" EQUALS "Type=x11")
set(display_server_x11 TRUE)
else()
set(display_server_x11 FALSE)
endif()
Probably you have to fiddle around with the condition and check for Type=wayland or similar to get it properly working in your environment.
You can use display_server_x11 and write it into a config.h file to use it within C++ code.

Drop commits by commit message in `git rebase`

I would like to do a git rebase and drop commits whose commit messages match a certain regular expression. For example, it might work like
git rebase --drop="deletme|temporary" master
And this would do a rebase over master while dropping all commits containing the string deleteme or temporary.
Is is possible to do this with the standard Git tool? If not, is it possible with a third-party Git tool? In particular, I want it to be a single, noninteractive command.
This can be accomplished using the same method as I used in this answer.
First, we need to find the relevant commits. You can do that with something like:
git log --format=format:"%H %s" master..HEAD | grep -E "deleteme|temporary"
This will give you a list of commits with commit messages containing deleteme or temporary that are between master and your current branch. These are the commits that need to be dropped.
Save this bash script somewhere you can access it:
#!/bin/bash
for sha in $(git log --format=format:"%H %s" master..HEAD | grep -E "deleteme|temporary" | cut -d " " -f 1)
do
sha=${sha:0:7}
sed -i "s/pick $sha/drop $sha/" $#
done
Then run the rebase as:
GIT_SEQUENCE_EDITOR=/path/to/script.sh git rebase -i
This will automatically drop all commits that contain deleteme or temporary in their commit message.
As mentioned in my other answer:
[This script won't allow] you to customize what command is run to calculate which commits to use, but if this is an issue, you could probably pass in an environment variable to allow such customization.
Obligatory warning: Since a rebase rewrites history, this can be dangerous / disruptive for anyone else working on this branch. Be sure you clearly communicate what you have done with anyone you are collaborating with.
You could e. g. use interactive rebase. So do git rebase -i <first commit that should not be touched>, and then in vim where you have the list of commits, you can do :%s/^[^ ]* \([^ ]* issue\)/d \1/g to use drop stanza for all commits whose commit message starts with issue. But be aware that git rebase is not working optimally with merge commits. By default they are skipped and the history flattened, but you can try to keep them with parameters.
#Scott Weldon's answer works great for this usecase, however If the regex checks from the start of the message for example with (^(deleteme)|^(temporary)), then this won't work, since the start of the grep is the commit hash. So in that case you can use this instead
#!/bin/bash
for sha in $(git log --format=format:"%s %H" master..HEAD | grep -E "^(deleteme)|^(temporary)" | awk '{print $NF}')
do
sha=${sha:0:7}
sed -i "s/pick $sha/drop $sha/" $#
done
The core difference is that %sand %H swapped places, and therefore we search the last part of the string instead of the first part of the string by piping to awk '{print $NF}')
Also worth noting that this is called the same way as in Scott Weldon's answer:
GIT_SEQUENCE_EDITOR=/path/to/script.sh git rebase -i master

Updating version numbers before git commit using OS X Bash sed

I wish to use git log --oneline | wc -l to provide the revision number for sed substitution in the following Lua file (simplified) during each commit using a script and $GIT/hooks:
-- settings.lua
local module = {}
-- major, minor, build, and revision number
module.version = "10.0.0.0"
return module
I'm testing from the command-line with this:
sed -E 's/(version\s*=\s*\"\d+\.\d+\.\d+\.)/\1foo"/' settings.lua
All sed outputs is the following verbatim copy of the input:
-- settings.lua
local module = {}
-- major, minor, build, and revision number
module.version = "10.0.0.0"
return module
I must be totally misunderstanding the things I'm ready about sed and its purpose in life. Coming from a 20 years background C/C++ and in now C# I'm amazed I can't get my head around this. I know that pattern matches!
My sed understanding is that it will match version = "10.0.0.0" and then change the entire matched string to version = "10.0.0.foo" which once done I can simple " and a > settings.au to replace the original file with the substation in place.
As usual I've drifted way too far off track thinking something was going to be simple but wasn't and just because I want it. I was really enjoying the Lua part too.
In sed, \d wouldn't work the way you expect it to work. Use [0-9] or [[:digit:]] instead of \d
EDIT
Another way to do it:
sed -i.bak '/module.version/s/"$/foo"/' File
AMD$ cat File
-- settings.lua
local module = {}
-- major, minor, build, and revision number
module.version = "10.0.0.0foo"
return module
For lines matching module.version, substitute the last " with foo".
The above command will edit the file inplace, keeping a backup.

How to substitute words in Git history & properly debug related problems?

I'm trying to remove sensitive data like passwords from my Git history. Instead of deleting whole files I just want to substitute the passwords with removedSensitiveInfo. This is what I came up with after browsing through numerous StackOverflow topics and other sites.
git filter-branch --tree-filter "find . -type f -exec sed -Ei '' -e 's/(aSecretPassword1|aSecretPassword2|aSecretPassword3)/removedSensitiveInfo/g' {} \;"
When I run this command it seems to be rewriting the history (it shows the commits it's rewriting and takes a few minutes). However, when I check to see if all sensitive data has indeed been removed it turns out it's still there.
For reference this is how I do the check
git grep aSecretPassword1 $(git rev-list --all)
Which shows me all the hundreds of commits that match the search query. Nothing has been substituted.
Any idea what's going on here?
I double checked the regular expression I'm using which seems to be correct. I'm not sure what else to check for or how to properly debug this as my Git knowledge quite rudimentary. For example I don't know how to test whether 1) my regular expression isn't matching anything, 2) sed isn't being run on all files, 3) the file changes are not being saved, or 4) something else.
Any help is very much appreciated.
P.S.
I'm aware of several StackOverflow threads about this topic. However, I couldn't find one that is about substituting words (rather than deleting files) in all (ASCII) files (rather than specifying a specific file or file type). Not sure whether that should make a difference, but all suggested solutions haven't worked for me.
git-filter-branch is a powerful but difficult to use tool - there are several obscure things you need to know to use it correctly for your task, and each one is a possible cause for the problems you're seeing. So rather than immediately trying to debug them, let's take a step back and look at the original problem:
Substitute given strings (ie passwords) within all text files (without specifying a specific file/file-type)
Ensure that the updated Git history does not contain the old password text
Do the above as simply as possible
There is a tailor-made solution to this problem:
Use The BFG... not git-filter-branch
The BFG Repo-Cleaner is a simpler alternative to git-filter-branch specifically designed for removing passwords and other unwanted data from Git repository history.
Ways in which the BFG helps you in this situation:
The BFG is 10-720x faster
It automatically runs on all tags and references, unlike git-filter-branch - which only does that if you add the extraordinary --tag-name-filter cat -- --all command-line option (Note that the example command you gave in the Question DOES NOT have this, a possible cause of your problems)
The BFG doesn't generate any refs/original/ refs - so no need for you to perform an extra step to remove them
You can express you passwords as simple literal strings, without having to worry about getting regex-escaping right. The BFG can handle regex too, if you really need it.
Using the BFG
Carefully follow the usage steps - the core bit is just this command:
$ java -jar bfg.jar --replace-text replacements.txt my-repo.git
The replacements.txt file should contain all the substitutions you want to do, in a format like this (one entry per line - note the comments shouldn't be included):
PASSWORD1 # Replace literal string 'PASSWORD1' with '***REMOVED***' (default)
PASSWORD2==>examplePass # replace with 'examplePass' instead
PASSWORD3==> # replace with the empty string
regex:password=\w+==>password= # Replace, using a regex
Your entire repository history will be scanned, and all text files (under 1MB in size) will have the substitutions performed: any matching string (that isn't in your latest commit) will be replaced.
Full disclosure: I'm the author of the BFG Repo-Cleaner.
Looks OK. Remember that filter-branch retains the original commits under refs/original/, e.g.:
$ git commit -m 'add secret password, oops!'
[master edaf467] add secret password, oops!
1 file changed, 4 insertions(+)
create mode 100644 secret
$ git filter-branch --tree-filter "find . -type f -exec sed -Ei '' -e 's/(aSecretPassword1|aSecretPassword2|aSecretPassword3)/removedSensitiveInfo/g' {} \;"
Rewrite edaf467960ade97ea03162ec89f11cae7c256e3d (2/2)
Ref 'refs/heads/master' was rewritten
Then:
$ git grep aSecretPassword `git rev-list --all`
edaf467960ade97ea03162ec89f11cae7c256e3d:secret:aSecretPassword2
but:
$ git lola
* e530e69 (HEAD, master) add secret password, oops!
| * edaf467 (refs/original/refs/heads/master) add secret password, oops!
|/
* 7624023 Initial
(git lola is my alias for git log --graph --oneline --decorate --all). Yes, it's in there, but under the refs/original name space. Clear that out:
$ rm -rf .git/refs/original
$ git reflog expire --expire=now --all
$ git gc
Counting objects: 6, done.
Delta compression using up to 8 threads.
Compressing objects: 100% (4/4), done.
Writing objects: 100% (6/6), done.
Total 6 (delta 0), reused 0 (delta 0)
and then:
$ git grep aSecretPassword `git rev-list --all`
$
(as always, run filter-branch on a copy of the repo Just In Case; and then removing original refs, expiring the reflog "now", and gc'ing, means stuff is Really Gone).

Conditional statement using rexep with bash

I want to use the "conditional regexp" structure from bash, present since the third version of bash (circa 2004).
It's supposed to go like this:
if [[ $string =~ $regexp ]]; then
#do smthg
else
#do somthg else
fi
So here's my code, following this structure, and its role is to check if the name contained in SSID is presend in the output from iw dev wlan0 link :
if [[ $(iw dev wlan0 link) =~ $SSID+ ]]; then
#do sthming
else
echo "wrong network"
fi
For some reason that i can't decipher, this statement works pretty well if I run it right into the bash shell, like
if [[ $(iw dev wlan0 link) =~ $SSID+ ]]; then echo found; else echo not found; fi
But if i run it inside the script its contained, it'll spit out:
scripts/ssidchecker.sh: 22: [[: not found
22 being the line of the "fi" keyword. The strangest thing is that it will always execute the code contained in the "else" statement
Is "not found" meant to indicate me that the regexp dind't find anything in that string? Is it a real error message?
Starting Note: Answer created with input from comments in question, especially in response of the last comment.
First, what is [[? It is a shell keyword.
samveen#maverick:~$ type [[
[[ is a shell keyword
This means that [[ is an internal keyword of bash, not a command and thus will not work with other shells. Thus, your error output
scripts/ssidchecker.sh: 22: [[: not found
means that the shell you're using is probably
Not bash
A version of bash older than 2.02 ([[ introduced in Bash-2.02)
Given that 2.02 is a really really old version (pre Y2K), all this just points to the fact that the shell you're using to run the script is probably not /bin/bash, instead probably being /bin/sh which is the most common path used for Bourne shell scripts shebang (the #!) line.
Please change that to /bin/bash or explicitly run bash scripts/ssidchecker.sh and you're good to go.
As to why the else section was always executed, the [[ command not being found is the same as a failure (non-zero return value), from the viewpoint of if. Thus the else section is executed.
samveen#maverick:~$ /bin/whosyourdaddy
-bash: /bin/whosyourdaddy: No such file or directory
samveen#maverick:~$ echo $?
127
As a side note on portability, the bash hackers wiki also says the following about the [[ keyword:
Amongst the major "POSIX-shell superset languages" (for lack of a
better term) which do have [[, the test expression compound command is
one of the very most portable non-POSIX features. Aside from the =~
operator, almost every major feature is consistent between Ksh88,
Ksh93, mksh, Zsh, and Bash. Ksh93 also adds a large number of unique
pattern matching features not supported by other shells including
support for several different regex dialects, which are invoked using
a different syntax from Bash's =~, though =~ is still supported by ksh
and defaults to ERE.
Thus your script will probably fail on the =~ even if the shell supports [[, in case the shell isn't bash but supports [[.