Convert newlines to spaces
February 16, 2018
TR can be used to convert a list of items from one per line to space separated with this:
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tr '\r\n' ' ' |
TR can be used to convert a list of items from one per line to space separated with this:
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tr '\r\n' ' ' |
Posting this because I always forget and have to goggle for the answer. The default “vi” installed with Ubuntu has terminal emulation problems on both Ubuntu Desktop and through putty. The fix is simple … install “vim” …
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sudo apt install vim |
CentOS uses the libjpeg-turbo fork of the original libjpeg project. So to install jpegtran do this:
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yum install libjpeg-turbo-utils |
Recently needed a good way to fetch the IP address of each interface within a script. Tried things like:
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ifconfig | grep 'inet addr:'| grep -v '127.0.0.1' | cut -d: -f2 | awk '{ print $1}' |
and
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/sbin/ifconfig | sed -n '2 p' | awk '{print $3}' |
But this is fairly ugly. So I tried:
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hostname -I |
This gives a list of IP addresses but they are un-ordered so I can’t guarantee which address goes with which interface. Here’s one using “ip addr”:
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ip=$(ip -f inet -o addr show eth0|cut -d\ -f 7 | cut -d/ -f 1) |
Still very messy. Finally, found the “ifdata” command which is part of the “moreutils” package. First make sure “moreutils” is installed with:
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yum -y install moreutils |
Now you can query for a wide range of different information:
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Usage: ifdata [options] iface -e Reports interface existence via return code -p Print out the whole config of iface -pe Print out yes or no according to existence -pa Print out the address -pn Print netmask -pN Print network address -pb Print broadcast -pm Print mtu -ph Print out the hardware address -pf Print flags -si Print all statistics on input -sip Print # of in packets -sib Print # of in bytes -sie Print # of in errors -sid Print # of in drops -sif Print # of in fifo overruns -sic Print # of in compress -sim Print # of in multicast -so Print all statistics on output -sop Print # of out packets -sob Print # of out bytes -soe Print # of out errors -sod Print # of out drops -sof Print # of out fifo overruns -sox Print # of out collisions -soc Print # of out carrier loss -som Print # of out multicast -bips Print # of incoming bytes per second -bops Print # of outgoing bytes per second |
So here are some examples:
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[root@host]# ifdata -pa eth0 10.210.160.53 [root@host]# ifdata -pa eth0 10.210.160.53 [root@host]# ifdata -pn eth0 255.255.224.0 [root@host]# ifdata -sip eth0 1622384587 [root@host]# ifdata -bops eth0 896 |
Overall this is much cleaner and more reliable then the earlier approaches.
On October 19, 2016, a privilege escalation vulnerability in the Linux kernel was disclosed. The bug is nicknamed Dirty COW because the underlying issue was a race condition in the way kernel handles copy-on-write (COW). Dirty COW has existed for a long time — at least since 2007, with kernel version 2.6.22 — so the vast majority of servers are at risk. Exploiting this bug means that a regular, unprivileged user on your server can gain write access to any file they can read, and can therefore increase their privileges on the system. More information can be found on CVE-2016-5195 from Canonical, Red Hat, and Debian. Fortunately, most major distributions have already released a fix. You can follow this tutorial to see if your server is vulnerable and to apply updates as needed. Check Vulnerability Ubuntu/Debian To find out if your server is affected, check your kernel version. uname -rv
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