[PATCH v2 1/3] simplify updating GRUB_CMDLINE_LINUX in GRUB_ETC_DEFAULT

[Coiby Xu]

Use sed command group and conditional control to get rid of grep.

Suggested-by: Philipp Rudo <prudo(a)redhat.com&gt;
Signed-off-by: Coiby Xu <coxu(a)redhat.com&gt;
---
 kdumpctl | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/kdumpctl b/kdumpctl
index 9fd76ac..998ac6e 100755
--- a/kdumpctl
+++ b/kdumpctl
@@ -1405,19 +1405,22 @@ GRUB_ETC_DEFAULT="/etc/default/grub"
 # $2: new value. If empty, the parameter would be removed
 _update_kernel_cmdline_in_grub_etc_default()
 {
-	local _para=$1 _val=$2 _para_val _regex
+	local _para=$1 _val=$2 _para_val
 
 	if [[ -n $_val ]]; then
 		_para_val="$_para=$_val"
 	fi
 
-	_regex='^(GRUB_CMDLINE_LINUX=.*)([[:space:]"])'"$_para"'=[^[:space:]"]*(.*)$'
-	if grep -q -E "$_regex" "$GRUB_ETC_DEFAULT"; then
-		sed -i -E
's/'"$_regex"'/\1\2'"$_para_val"'\3/'
"$GRUB_ETC_DEFAULT"
-	elif [[ -n $_para_val ]]; then
-		# If the kernel parameter doesn't exist, put it in the first
-		sed -i -E 's/^(GRUB_CMDLINE_LINUX=")/\1'"$_para_val"' /'
"$GRUB_ETC_DEFAULT"
-	fi
+	# If the parameter already exists, replace it with new value.
+	# Otherwise insert it to the end.
+	sed -i -E "/^GRUB_CMDLINE_LINUX=/ {
+	          
s/([[:space:]\"])crashkernel=[^[:space:]\"]*(.*)$/\1${_para_val}\2/;
+	           # t: jump to a label only if a s/// command has succeeded.
+	           #    Since there is no label, it would jump to the end i.e.
+	           #    skip the last command if the parameter already exist
+	           t;
+	           s/\"$/ ${_para_val}\"/
+          }" "$GRUB_ETC_DEFAULT"
 }
 
 reset_crashkernel()
-- 
2.34.1

[PATCH v2 2/3] add a helper function to read kernel cmdline parameter from GRUB_ETC_DEFAULT

[Coiby Xu]

This function would be used to read kernel cmdline parameter like fadump
or crashkernel.

Signed-off-by: Coiby Xu <coxu(a)redhat.com&gt;
---
 kdumpctl | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kdumpctl b/kdumpctl
index 998ac6e..42730cb 100755
--- a/kdumpctl
+++ b/kdumpctl
@@ -1423,6 +1423,14 @@ _update_kernel_cmdline_in_grub_etc_default()
           }" "$GRUB_ETC_DEFAULT"
 }
 
+# read the kernel command line parameter in default grub conf
+#
+# $1: the name of the kernel command line parameter
+_read_kernel_cmdline_in_grub_etc_default()
+{
+	sed -n -E
"s/^GRUB_CMDLINE_LINUX=.*[[:space:]\"]${1}=([^[:space:]\"]*).*$/\1/p"
"$GRUB_ETC_DEFAULT"
+}
+
 reset_crashkernel()
 {
 	local _opt _val _dump_mode _fadump_val _reboot _grubby_kernel_path _kernel _kernels
-- 
2.34.1

[PATCH v2 3/3] try to update the crashkernel in GRUB_ETC_DEFAULT after kexec-tools updates the default crashkernel value

[Coiby Xu]

If GRUB_ETC_DEFAULT use crashkernel=auto or
crashkernel=OLD_DEFAULT_CRASHKERNEL, it should be updated as well.

Signed-off-by: Coiby Xu <coxu(a)redhat.com&gt;
---
 kdumpctl | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/kdumpctl b/kdumpctl
index 42730cb..5027f47 100755
--- a/kdumpctl
+++ b/kdumpctl
@@ -1562,6 +1562,34 @@ reset_crashkernel()
 	fi
 }
 
+# update the crashkernel value in GRUB_ETC_DEFAULT if necessary
+#
+# called by reset_crashkernel_after_update and inherit its array variable
+# _crashkernel_vals
+update_crashkernel_in_grub_etc_default_after_update()
+{
+	local _crashkernel _fadump_val
+	local _dump_mode _old_default_crashkernel _new_default_crashkernel
+
+	_crashkernel=$(_read_kernel_cmdline_in_grub_etc_default crashkernel)
+
+	if [[ -z $_crashkernel ]]; then
+		return
+	fi
+
+	_fadump_val=$(read_kernel_cmdline_in_grub_etc_default fadump)
+	_dump_mode=$(get_dump_mode_by_fadump_val "$_fadump_val")
+
+	_old_default_crashkernel=${_crashkernel_vals[old_${_dump_mode}]}
+	_new_default_crashkernel=${_crashkernel_vals[new_${_dump_mode}]}
+
+	if [[ $_crashkernel == auto ]] ||
+		  [[ $_crashkernel == "$_old_default_crashkernel" &&
+		     $_new_default_crashkernel != "$_old_default_crashkernel" ]]; then
+			_update_kernel_cmdline_in_grub_etc_default crashkernel
"$_new_default_crashkernel"
+	fi
+}
+
 # shellcheck disable=SC2154 # false positive when dereferencing an array
 reset_crashkernel_after_update()
 {
@@ -1590,6 +1618,8 @@ reset_crashkernel_after_update()
 			fi
 		fi
 	done
+
+	update_crashkernel_in_grub_etc_default_after_update
 }
 
 # read the value of an environ variable from given environ file path
-- 
2.34.1

[Coiby Xu]

Sorry, I missed one patch and have resent v2. Please ignore this patch
set.

On Wed, Feb 16, 2022 at 01:23:17PM +0800, Coiby Xu wrote:
> Use sed command group and conditional control to get rid of grep.
>
> Suggested-by: Philipp Rudo <prudo(a)redhat.com&gt;
> Signed-off-by: Coiby Xu <coxu(a)redhat.com&gt;
> ---
>  kdumpctl | 19 +++++++++++--------
>  1 file changed, 11 insertions(+), 8 deletions(-)
>
> diff --git a/kdumpctl b/kdumpctl
> index 9fd76ac..998ac6e 100755
> --- a/kdumpctl
> +++ b/kdumpctl
> @@ -1405,19 +1405,22 @@ GRUB_ETC_DEFAULT="/etc/default/grub"
>  # $2: new value. If empty, the parameter would be removed
>  _update_kernel_cmdline_in_grub_etc_default()
>  {
> -	local _para=$1 _val=$2 _para_val _regex
> +	local _para=$1 _val=$2 _para_val
>
>  	if [[ -n $_val ]]; then
>  		_para_val="$_para=$_val"
>  	fi
>
> -	_regex='^(GRUB_CMDLINE_LINUX=.*)([[:space:]"])'"$_para"'=[^[:space:]"]*(.*)$'
> -	if grep -q -E "$_regex" "$GRUB_ETC_DEFAULT"; then
> -		sed -i -E
> 's/'"$_regex"'/\1\2'"$_para_val"'\3/'
> "$GRUB_ETC_DEFAULT"
> -	elif [[ -n $_para_val ]]; then
> -		# If the kernel parameter doesn't exist, put it in the first
> -		sed -i -E 's/^(GRUB_CMDLINE_LINUX=")/\1'"$_para_val"' /'
> "$GRUB_ETC_DEFAULT"
> -	fi
> +	# If the parameter already exists, replace it with new value.
> +	# Otherwise insert it to the end.
> +	sed -i -E "/^GRUB_CMDLINE_LINUX=/ {
> +	          
> s/([[:space:]\"])crashkernel=[^[:space:]\"]*(.*)$/\1${_para_val}\2/;
> +	           # t: jump to a label only if a s/// command has succeeded.
> +	           #    Since there is no label, it would jump to the end i.e.
> +	           #    skip the last command if the parameter already exist
> +	           t;
> +	           s/\"$/ ${_para_val}\"/
> +          }" "$GRUB_ETC_DEFAULT"
>  }
>
>  reset_crashkernel()
> -- 
> 2.34.1
>  
-- 
Best regards,
Coiby