If `egrep` is aliased, temporary disable it in bash.completion

PATCH In review Adam Tkac 3 participants 6 messages Jun 15, 2016

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Adam Tkac

author

2016-06-15 22:55 UTC #0 lore raw

PATCH v2 1/1 If `egrep` is aliased, temporary disable it in bash.completion

Originally reported as https://bugzilla.redhat.com/show_bug.cgi?id=863780

Signed-off-by Adam Tkac <[email protected]>

Signed-off-by Holger Arnold <[email protected]>

---
 contrib/completion/git-completion.bash | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

contrib/completion/git-completion.bash +1 -1

index 0960acc..79073c2 100644
@@ -565,7 +565,7 @@ __git_complete_strategy ()
 __git_list_all_commands ()
 {
 	local i IFS=" "$'\n'
-	for i in $(git help -a|egrep '^  [a-zA-Z0-9]')
+	for i in $(git help -a| \egrep '^  [a-zA-Z0-9]')
 	do
 		case $i in
 		*--*)             : helper pattern;;

Signature · 5 lines

1.8.0


-- 
Adam Tkac, Red Hat, Inc.

Junio C Hamano

2016-06-15 22:55 UTC #1 lore raw

Quoted 1 line · Adam Tkac

Subject: Re: [PATCH v2] If egrep is aliased, temporary disable it in bash.completion

The code does not seem to do anything special if it is not aliased, though, so "If ..." part does not sound correct; perhaps you meant "just in case egrep is aliased to something totally wacky" or something?

The script seems to use commands other than 'egrep' that too can be aliased to do whatever unexpected things. How does this patch get away without backslashing them all, like

	\echo ...
        \sed ...
        \test ...
        \: comment ...
	\git args ...

and still fix problems for users? Can't the same solution you would give to users who alias one of the above to do something undesirable be applied to those who alias egrep?

Puzzled...

Quoted 23 lines

Originally reported as https://bugzilla.redhat.com/show_bug.cgi?id=863780
Signed-off-by Adam Tkac <[email protected]>
Signed-off-by Holger Arnold <[email protected]>
---
 contrib/completion/git-completion.bash | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
contrib/completion/git-completion.bash +1 -1
index 0960acc..79073c2 100644
@@ -565,7 +565,7 @@ __git_complete_strategy ()
 __git_list_all_commands ()
 {
 	local i IFS=" "$'\n'
-	for i in $(git help -a|egrep '^  [a-zA-Z0-9]')
+	for i in $(git help -a| \egrep '^  [a-zA-Z0-9]')
 	do
 		case $i in
 		*--*)             : helper pattern;;
Signature · 1 line
1.8.0

Junio C Hamano

2016-06-15 22:55 UTC #2 lore raw

Quoted 19 lines · Junio C Hamano

Quoted 1 line · Adam Tkac
Subject: Re: [PATCH v2] If egrep is aliased, temporary disable it in bash.completion
The code does not seem to do anything special if it is not aliased, though, so "If ..." part does not sound correct; perhaps you meant "just in case egrep is aliased to something totally wacky" or something?
The script seems to use commands other than 'egrep' that too can be aliased to do whatever unexpected things. How does this patch get away without backslashing them all, like
	\echo ...
        \sed ...
        \test ...
        \: comment ...
	\git args ...

Quoted 5 lines

and still fix problems for users? Can't the same solution you would give to users who alias one of the above to do something undesirable be applied to those who alias egrep?
Puzzled...

Sorry for having been more snarky than necessary (blame it to lack of caffeine). What I was trying to get at were:

* I have this suspicion that this patch exists only because you saw somebody who aliases egrep to something unexpected by the use of it in this script, and egrep *happened* to be the only such "unreasonable" alias. The reporter may not have aliased echo or sed away, or the aliases to these command *happened* to produce "acceptable" output (even though it might have been slightly different from unaliased one, the difference *happened* not to matter for the purpose of this script).

* To the person who observes the same aliasing breakage due to his aliasing sed to something else, you would solve his problem by telling him "don't do that, then". If that is the solution, why wouldn't it work for egrep?

* The next person who aliased other commands this script uses in such a way that the behaviour of the alias differs sufficiently from the unaliased version, you will have to patch the file again, with the same backslashing. This patch is not a solution, but a band-aid that only works for a particular case you *happened* to have seen.

* A complete solution that follows the direction this patch suggests would involve backslashing *all* commands that can potentially aliased away. Is that really the direction we would want to go in (answer: I doubt it)? Is that the only approach to solve this aliasing issue (answer: I don't know, but we should try to pursue it before applying a band-aid that is not a solution)?

Is there a way to tell bash "do not alias-expand from here up to there"? Perhaps "shopt -u expand_aliases" upon entry and restore its original value when we exit, or something?

IOW, something along this line?

 contrib/completion/git-completion.bash | 13 +++++++++++++
 1 file changed, 13 insertions(+)

contrib/completion/git-completion.bash +13 -0

index 0b77eb1..193f53c 100644
@@ -23,6 +23,14 @@
 #    3) Consider changing your PS1 to also show the current branch,
 #       see git-prompt.sh for details.
 
+if shopt -q expand_aliases
+then
+	_git__aliases_were_enabled=yes
+else
+	_git__aliases_were_enabled=
+fi
+shopt -u expand_aliases
+
 case "$COMP_WORDBREAKS" in
 *:*) : great ;;
 *)   COMP_WORDBREAKS="$COMP_WORDBREAKS:"

@@ -2504,3 +2512,8 @@ __git_complete gitk __gitk_main
 if [ Cygwin = "$(uname -o 2>/dev/null)" ]; then
 __git_complete git.exe __git_main
 fi
+
+if test -n "$_git__aliases_were_enabled"
+then
+	shopt -s expand_aliases
+fi

Adam Tkac

author

2016-06-15 22:55 UTC #3 lore raw

Quoted 59 lines · Junio C Hamano

Quoted 19 lines · Junio C Hamano
Quoted 1 line · Adam Tkac
Subject: Re: [PATCH v2] If egrep is aliased, temporary disable it in bash.completion
The code does not seem to do anything special if it is not aliased, though, so "If ..." part does not sound correct; perhaps you meant "just in case egrep is aliased to something totally wacky" or something?
The script seems to use commands other than 'egrep' that too can be aliased to do whatever unexpected things. How does this patch get away without backslashing them all, like
	\echo ...
        \sed ...
        \test ...
        \: comment ...
	\git args ...
Quoted 5 lines
and still fix problems for users? Can't the same solution you would give to users who alias one of the above to do something undesirable be applied to those who alias egrep?
Puzzled...
Sorry for having been more snarky than necessary (blame it to lack of caffeine). What I was trying to get at were:
* I have this suspicion that this patch exists only because you saw somebody who aliases egrep to something unexpected by the use of it in this script, and egrep *happened* to be the only such "unreasonable" alias. The reporter may not have aliased echo or sed away, or the aliases to these command *happened* to produce "acceptable" output (even though it might have been slightly different from unaliased one, the difference *happened* not to matter for the purpose of this script).
* To the person who observes the same aliasing breakage due to his aliasing sed to something else, you would solve his problem by telling him "don't do that, then". If that is the solution, why wouldn't it work for egrep?
* The next person who aliased other commands this script uses in such a way that the behaviour of the alias differs sufficiently from the unaliased version, you will have to patch the file again, with the same backslashing. This patch is not a solution, but a band-aid that only works for a particular case you *happened* to have seen.
* A complete solution that follows the direction this patch suggests would involve backslashing *all* commands that can potentially aliased away. Is that really the direction we would want to go in (answer: I doubt it)? Is that the only approach to solve this aliasing issue (answer: I don't know, but we should try to pursue it before applying a band-aid that is not a solution)?

Quoted 5 lines

Is there a way to tell bash "do not alias-expand from here up to there"? Perhaps "shopt -u expand_aliases" upon entry and restore its original value when we exit, or something?
IOW, something along this line?

This won't work, unfortunately, because shopt settings aren't inherited by subshell (and for example egrep is called in subshell).

I discussed this issue with colleagues and we found basically two "fixes":

1. Tell people "do not use aliases which breaks completion script"
2. Prefix all commands with "command", i.e. command egrep etc.

In my opinion "2." is better long time solution, what do you think?

Regards, Adam

Quoted 34 lines

 contrib/completion/git-completion.bash | 13 +++++++++++++
 1 file changed, 13 insertions(+)

contrib/completion/git-completion.bash +13 -0

index 0b77eb1..193f53c 100644
@@ -23,6 +23,14 @@
 #    3) Consider changing your PS1 to also show the current branch,
 #       see git-prompt.sh for details.
 
+if shopt -q expand_aliases
+then
+	_git__aliases_were_enabled=yes
+else
+	_git__aliases_were_enabled=
+fi
+shopt -u expand_aliases
+
 case "$COMP_WORDBREAKS" in
 *:*) : great ;;
 *)   COMP_WORDBREAKS="$COMP_WORDBREAKS:"

@@ -2504,3 +2512,8 @@ __git_complete gitk __gitk_main
 if [ Cygwin = "$(uname -o 2>/dev/null)" ]; then
 __git_complete git.exe __git_main
 fi
+
+if test -n "$_git__aliases_were_enabled"
+then
+	shopt -s expand_aliases
+fi

Signature · 1 line

Adam Tkac, Red Hat, Inc.

Junio C Hamano

2016-06-15 22:55 UTC #4 lore raw

Quoted 7 lines · Adam Tkac

On Thu, Nov 29, 2012 at 09:33:53AM -0800, Junio C Hamano wrote:
...
Quoted 1 line
IOW, something along this line?
This won't work, unfortunately, because shopt settings aren't inherited by subshell (and for example egrep is called in subshell).

Quoted 6 lines

I discussed this issue with colleagues and we found basically two "fixes":
1. Tell people "do not use aliases which breaks completion script"
2. Prefix all commands with "command", i.e. command egrep etc.
In my opinion "2." is better long time solution, what do you think?

Judging from what is in /etc/bash_completion.d/ (I am on Debian), I think that others are divided. Many but not all prefix "command" in front of "grep", but nobody does the same for "egrep", "cut", "tr", "sed", etc.

If it were up to me, I would say we pick #1, but I cc'ed the people who have been more involved in our bash-completion code because they are in a better position to argue between the two than I am.

Thoughts?

Felipe Contreras

2016-06-15 22:55 UTC #5 lore raw

Quoted 16 lines · Junio C Hamano

Quoted 7 lines · Adam Tkac
On Thu, Nov 29, 2012 at 09:33:53AM -0800, Junio C Hamano wrote:
...
Quoted 1 line
IOW, something along this line?
This won't work, unfortunately, because shopt settings aren't inherited by subshell (and for example egrep is called in subshell).
Quoted 6 lines
I discussed this issue with colleagues and we found basically two "fixes":
1. Tell people "do not use aliases which breaks completion script"
2. Prefix all commands with "command", i.e. command egrep etc.
In my opinion "2." is better long time solution, what do you think?

Quoted 8 lines

Judging from what is in /etc/bash_completion.d/ (I am on Debian), I think that others are divided. Many but not all prefix "command" in front of "grep", but nobody does the same for "egrep", "cut", "tr", "sed", etc.
If it were up to me, I would say we pick #1, but I cc'ed the people who have been more involved in our bash-completion code because they are in a better position to argue between the two than I am.

Why not both? I do prefer #1, but I don't see why we wouldn't prefix some commonly problematic ones (\egrep), prefixing all of them seems overkill for me.

Signature · 1 line

Felipe Contreras