Jhorne: /* Useful ways to use Sed in Linux */

2022-05-06T19:34:03Z

Useful ways to use Sed in Linux

← Older revision		Revision as of 19:34, 6 May 2022
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	To uncomment something in a config file:		To uncomment something in a config file:
	sed -i 's/^#compress/compress/' /etc/logrotate.conf		sed -i 's/^#compress/compress/' /etc/logrotate.conf
			sed -i 's/^#UseDNS no/UseDNS no/' /etc/ssh/sshd_config
	To remove "rhgb quiet" from grub.conf:		To remove "rhgb quiet" from grub.conf:
	sed -i 's/rhgb quiet//g' /boot/grub/grub.conf		sed -i 's/rhgb quiet//g' /boot/grub/grub.conf

Jhorne at 13:29, 28 July 2020

2020-07-28T13:29:29Z

← Older revision		Revision as of 13:29, 28 July 2020
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	[[Category:Linux]]		[[Category:Linux]]

			==Measure disk i/o performance==
			dd if=/dev/zero of=outfile bs=1M count=1024 conv=fdatasync; rm -rf outfile
			dd if=/dev/zero of=outfile bs=1M count=2048 conv=fdatasync; rm -rf outfile
			dd if=/dev/zero of=outfile bs=1M count=4096 conv=fdatasync; rm -rf outfile

	==Refresh disk storage system after adding new disks==		==Refresh disk storage system after adding new disks==

Jhorne at 02:15, 20 August 2017

2017-08-20T02:15:34Z

← Older revision		Revision as of 02:15, 20 August 2017
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	[[Category:Linux]]		[[Category:Linux]]

			==Refresh disk storage system after adding new disks==
			for i in `ls /sys/class/scsi_host`; do echo "- - -" > /sys/class/scsi_host/${i}/scan; done

	==Useful Random Bash Command Line Usages==		==Useful Random Bash Command Line Usages==

Jhorne: Created page with "Category:Linux ==Useful Random Bash Command Line Usages== To find all matching files names in a directory hierarchy find /path/to/dir -type f | rev | sort | sed -nr ':a..."

2016-12-29T16:39:49Z

Created page with "Category:Linux ==Useful Random Bash Command Line Usages== To find all matching files names in a directory hierarchy find /path/to/dir -type f | rev | sort | sed -nr ':a..."

New page

[[Category:Linux]]

==Useful Random Bash Command Line Usages==
To find all matching files names in a directory hierarchy
find /path/to/dir -type f | rev | sort | sed -nr ':a N;/^([^/]*\/).*\n\1/p;D;ba' | uniq | rev

==Useful ways to use Sed in Linux==
These first two examples are used in linux installation scripts as %post activities.

To uncomment something in a config file:
sed -i 's/^#compress/compress/' /etc/logrotate.conf
To remove "rhgb quiet" from grub.conf:
sed -i 's/rhgb quiet//g' /boot/grub/grub.conf

Examples from various task scripts which i will categeorize and label later: (some will be repeats)
<nowiki>
[root@d0lppb021 syssupport]# grep sed *.sh
addjhorne.sh:sed -i '/^jhorne/ c\jhorne:yaaaaaaaaaaaaaaaaaaaaaaaaaaaayyyyyyyyyyyyyyyyyyyyyy:0:99999:7:::' /etc/shadow
filesystem_lv_mysql-vg01-500G-sda.sh:sed -i '/lv_mysql/d' /etc/fstab
filesystem_lv_postgres-vg01-500G-sda.sh:sed -i '/lv_postgres/d' /etc/fstab
fixbacula.sh:sed -i "s/set-hostname/$HOSTNAME/g" /etc/bacula/bacula-fd.conf
fixpostfix.sh:sed -i "s/^#myhostname = virtual.domain.tld/myhostname = $HOSTNAME.skopos.me/g" /etc/postfix/main.cf
fixpostfix.sh:sed -i 's/^#mydomain = domain.tld/mydomain = skopos.us/' /etc/postfix/main.cf
fixpostfix.sh:sed -i 's/^#myorigin = $mydomain/myorigin = $mydomain/' /etc/postfix/main.cf
initialovirt.sh:sed -i 's/Santiago//g' /etc/redhat-release
initialovirt.sh:sed -i "s/set-hostname/$HOSTNAME/g" /etc/bacula/bacula-fd.conf
initialphysical.sh:sed -i 's/Santiago//g' /etc/redhat-release
initialphysical.sh:sed -i "s/set-hostname/$HOSTNAME/g" /etc/bacula/bacula-fd.conf
initialpxe.sh:sed -i "s/set-hostname/$HOSTNAME/g" /etc/bacula/bacula-fd.conf
initialvirtual.sh:sed -i "s/set-hostname/$HOSTNAME/g" /etc/bacula/bacula-fd.conf
readyesno.sh: [Yy]* ) umount /opt/mysql; pvcreate /dev/sda1; vgcreate vg01 /dev/sda1; lvcreate -L 500G -n lv_mysql vg01; mkfs.ext4 /dev/vg01/lv_mysql; sed -i '/lv_mysql/d' /etc/fstab; echo "/dev/mapper/vg01-lv_mysql /opt/mysql ext4 defaults,_netdev 0 0" >> /etc/fstab; cat /etc/fstab; mount -a; df -h; break;;
setupssl.sh:sed -i "s/localhost.crt/skopos.me.crt/g" /etc/httpd/conf.d/ssl.conf
setupssl.sh:sed -i "s/localhost.key/skopos.me.key/g" /etc/httpd/conf.d/ssl.conf
</nowiki>

This example is from to change a PXE profile file, to add ksdevice parameter:
sed -i 's/^ append initrd/ append ksdevice=em1 nicdelay=50 linksleep=50 initrd/' /tftpboot/linux-install/pxelinux.cfg/0*

==Yum Configuration to Skip a Package==
I have had a problem with Fedora overwriting the respository version of Cacti with the source version that I had previously installed. To prevent yum from updating a specific package, I have found this switch:
yum -y update --exclude=cacti
There is also a facility to handle this directly, from within /etc/yum/yum.conf.

Useful Linux Commands - Revision history

Jhorne: /* Useful ways to use Sed in Linux */

Jhorne at 13:29, 28 July 2020

Jhorne at 02:15, 20 August 2017

Jhorne: Created page with "Category:Linux ==Useful Random Bash Command Line Usages== To find all matching files names in a directory hierarchy find /path/to/dir -type f | rev | sort | sed -nr ':a..."