Libguestfs - Mar 2016 - [PATCH] appliance: use bash features for string matching in files

Read the content of /proc/cmdline using bash features, and use its
[[ ... ]] expression to find texts in a variable.

This shaves off 5 grep invocations.
---
 appliance/init | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/appliance/init b/appliance/init
index f6fe9b9..8d662fa 100755
--- a/appliance/init
+++ b/appliance/init
@@ -75,7 +75,9 @@ $UDEVD --daemon #--debug
 udevadm trigger
 udevadm settle --timeout=600
 
-if grep -sq selinux=1 /proc/cmdline; then
+cmdline=$(</proc/cmdline)
+
+if [[ $cmdline == *selinux=1* ]]; then
   mount -t selinuxfs none /sys/fs/selinux
 fi
 
@@ -91,16 +93,16 @@ shopt -u nullglob
 hwclock -u -s
 
 # Parse the kernel command line.
-if grep -sq guestfs_verbose=1 /proc/cmdline; then
+if [[ $cmdline == *guestfs_verbose=1* ]]; then
     guestfs_verbose=1
 fi
-if grep -sq guestfs_network=1 /proc/cmdline; then
+if [[ $cmdline == *guestfs_network=1* ]]; then
     guestfs_network=1
 fi
-if grep -sq guestfs_rescue=1 /proc/cmdline; then
+if [[ $cmdline == *guestfs_rescue=1* ]]; then
     guestfs_rescue=1
 fi
-if grep -sq guestfs_noreboot=1 /proc/cmdline; then
+if [[ $cmdline == *guestfs_noreboot=1* ]]; then
     guestfs_noreboot=1
 fi
 eval `grep -Eo 'guestfs_channel=[^[:space:]]+' /proc/cmdline`
-- 
2.5.5

On Tue, Mar 22, 2016 at 03:48:53PM +0100, Pino Toscano
wrote:
> Read the content of /proc/cmdline using bash features, and use its
> [[ ... ]] expression to find texts in a variable.
> 
> This shaves off 5 grep invocations.
> ---
>  appliance/init | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/appliance/init b/appliance/init
> index f6fe9b9..8d662fa 100755
> --- a/appliance/init
> +++ b/appliance/init
> @@ -75,7 +75,9 @@ $UDEVD --daemon #--debug
>  udevadm trigger
>  udevadm settle --timeout=600
>  
> -if grep -sq selinux=1 /proc/cmdline; then
> +cmdline=$(</proc/cmdline)
> +
> +if [[ $cmdline == *selinux=1* ]]; then
>    mount -t selinuxfs none /sys/fs/selinux
>  fi
>  
> @@ -91,16 +93,16 @@ shopt -u nullglob
>  hwclock -u -s
>  
>  # Parse the kernel command line.
> -if grep -sq guestfs_verbose=1 /proc/cmdline; then
> +if [[ $cmdline == *guestfs_verbose=1* ]]; then
>      guestfs_verbose=1
>  fi
> -if grep -sq guestfs_network=1 /proc/cmdline; then
> +if [[ $cmdline == *guestfs_network=1* ]]; then
>      guestfs_network=1
>  fi
> -if grep -sq guestfs_rescue=1 /proc/cmdline; then
> +if [[ $cmdline == *guestfs_rescue=1* ]]; then
>      guestfs_rescue=1
>  fi
> -if grep -sq guestfs_noreboot=1 /proc/cmdline; then
> +if [[ $cmdline == *guestfs_noreboot=1* ]]; then
>      guestfs_noreboot=1
>  fi
>  eval `grep -Eo 'guestfs_channel=[^[:space:]]+' /proc/cmdline`
ACK.

Rich.

-- 
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