How to determine the subnet mask and network interface card from remote SSH login?

Tag: linux,shell,ssh,network-programming,aix

In a separate question (link below), it was suggested that I obtain the network interface card number and subnet mask from a remote SSH login, rather than prompting the user for it. All I have is the IP address of my remote host. I need to obtain the subnet mask to determine if the remote and local host are on the same subnet, and the interface card number to set up and configure a virtual IP for aliasing purposes.

Could someone suggest how I might be able to parse out the necessary information and return it to my shell script that initiates the remote ssh connection? My target hosts have Linux or AIX as the operating system. I am familiar with the netstat function, but I'm not sure if parsing information from this is valid, or if there is a better way to get what I need that will work for both Linux and AIX operating systems.

Thanks for any help you can provide!

How to return from shell 'read' command passed in expect script?

--UPDATE--

AIX ifconfig -a:

$ ifconfig -a
en0: flags=1e080863,480<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST,GROUPR
T,64BIT,CHECKSUM_OFFLOAD(ACTIVE),CHAIN>
        inet 10.105.65.131 netmask 0xffff0000 broadcast 10.105.255.255
         tcp_sendspace 262144 tcp_recvspace 262144 rfc1323 1
lo0: flags=e08084b,c0<UP,BROADCAST,LOOPBACK,RUNNING,SIMPLEX,MULTICAST,GROUPRT,64
BIT,LARGESEND,CHAIN>
        inet 127.0.0.1 netmask 0xff000000 broadcast 127.255.255.255
        inet6 ::1%1/0
         tcp_sendspace 131072 tcp_recvspace 131072 rfc1323 1

AIX netstat -rn:

$ netstat -rn
Routing tables
Destination        Gateway           Flags   Refs     Use  If   Exp  Groups

Route tree for Protocol Family 2 (Internet):
default            10.105.65.1       UG       31  39412125 en0      -      -
10.105.0.0         10.105.65.131     UHSb      0         0 en0      -      -   =
>
10.105/16          10.105.65.131     U       219 985607244 en0      -      -
10.105.65.131      127.0.0.1         UGHS      5   1326738 lo0      -      -
10.105.255.255     10.105.65.131     UHSb      3   6926640 en0      -      -
127/8              127.0.0.1         U        36  11962928 lo0      -      -

Route tree for Protocol Family 24 (Internet v6):
::1%1              ::1%1             UH        1    393270 lo0      -      -

I tried route get and that doesn't work on my AIX box to tell me the route. The only thing I can get to work is netstat -rn. I'm not sure if there is another command similar to ip route that would work.

The Linux boxes support both ip and ifconfig.

I am not sure what to do when there are multiple network interface cards, as I do not know which one really should be used when setting up a virtual IP.

The Linux setup is more what I am concerned with, as I will be eventually adding in the AIX support for my software installation script later and can do more research on it then.

Best How To :

For Linux, I might do this something like so (using bash extensions, so invoked using a #!/bin/bash shebang, or piping the script over stdin to an interpreter invoked as ssh "$hostname" bash <<'EOF'):

internet_address=8.8.8.8 # read data for the NIC used to route here
dev_re='dev ([^[:space:]]+)($|[[:space:]])'
read default_route < <(ip -o route get "$internet_address")
[[ $default_route =~ $dev_re ]] && devname=${BASH_REMATCH[1]}

IFS=$'\n' read -r -d '' -a addresses < \
  <(netstat -rn | 
    awk -v dev="$devname" '$8 == dev && ($2 == "0.0.0.0" || $2 == "default") { print $1 }')

# emit this output however you like
printf '%s\n' "$dev_re" "${addresses[@]}"

Get system startup time (without reading /proc/uptime)

php,linux

You don't need the -s flag to determine the uptime. If you do something like this you have the time the server is running: $tmp = explode(' ', exec('uptime')); $uptime = $tmp[2]; // something like 2:14 (hh:mm) nb: an alternative would be to use the who -b command, which will...

What are correct permissions for Linux Apache2 PHP 5.3 log file?

php,linux,apache,logging,permissions

I'd simply set its owner to apache user. This will give you the name of apache user : ps aux | grep httpd In my case (CentOS), it's 'apache' but sometimes it's 'www-data'... chown apache:apache /var/log/httpd/php_errors.log chmod 600 /var/log/httpd/php_errors.log ...

AWK count number of times a term appear with respect to other columns

linux,shell,command-line,awk,sed

Almost same as the other answer, but printing 0 instead of blank. AMD$ awk -F, 'NR>1{a[$2]+=$3;b[$2]++} END{for(i in a)print i, a[i], b[i]}' File pear 1 1 apple 2 3 orange 0 1 peach 0 1 Taking , as field seperator. For all lines except the first, update array a. i.e...

How do I silence the HEAD of a curl request while using the silent flag?

bash,shell,curl,command-line,pipe

Try this: curl --silent "www.site.com" > file.txt ...

Linux - sh script - download multiple files from FTP

linux,ftp,sh

wget expect can be tricky to work with so I'd prefer to use GNU Wget as an alternative. The following should work as long as you don’t have any spaces in any of the arguments. for v in "${files_to_download[@]}" do ftp_file="${v}.bz2" wget --user=${USER} --password=${PASSWD} ${HOST}/${ftp_file} done Request multiple resources using...

Java read bytes from Socket on Linux

linux,windows,sockets,network-programming,raspberry-pi

InputStream input = client.getInputStream(); BufferedReader in = new BufferedReader(new InputStreamReader(input)); Your problem is here. You can't use multiple inputs on a socket when one or more of them is buffered. The buffered input stream/reader will read-ahead and 'steal' data from the other stream. You need to change your protocol so...

Identifying when a file is changed- Bash

bash,shell,unix

I would store the output of find, and if non-empty, echo the line break: found=$(find . -name "${myarray[i]}") if [[ -n $found ]]; then { echo "$found"; echo " "; } >> "$tmp" fi ...

sed string with special character New

linux,sed,special-characters

Escape / with \: sed -i 's/mrm.fr.mycompany.com/10.70.89.40:8081\/artifactory/' config.xml Or use this: sed -i 's|mrm.fr.mycompany.com|10.70.89.40:8081/artifactory|' config.xml ...

Using the shell provided with NodeJS

javascript,node.js,shell,require,node-modules

As per issue #5431, looks like the Node.JS REPL doesn't find globally-installed modules and this is expected behaviour. In the article linked from that issue, it reads: If you’re installing something that you want to use in your program, using require('whatever'), then install it locally, at the root of your...

Syncing Vagrant VMs across different physical servers

linux,vagrant,backup,virtual-machine,sync

Vagrant doesn't inherently support this, since it's intended audience is really development environments. It seems like you're looking for something more like what VMWare vSphere does.

Django MySQLClient pip compile failure on Linux

python,linux,django,gcc,pip

It looks like you're missing zlib; you'll want to install it: apt-get install zlib1g-dev I also suggest reading over the README and confirming you have all other dependencies met: https://github.com/dccmx/mysqldb/blob/master/README Also, I suggest using mysqlclient over MySQLdb as its a fork of MySQLdb and what Django recommends....

ret_from_syscall source code and when it is called

linux,linux-kernel,kernel,linux-device-driver,system-calls

The ret_from_syscall symbol will be in architecture-specific assembly code (it does not exist for all architectures). I would look in arch/XXX/kernel/entry.S. It's not actually a function. It is part of the assembly code that handles the transition from user-space into kernel-space for a system call. It's simply a label to...

how to deletes line from a text file that are taken from another file [duplicate]

shell,awk,sed,grep,sh

Something like this with grep: grep -vxf lines.txt data.txt > no_dupplicate_lines.txt Sample: AMD$ cat lines.txt Line2 Line4 AMD$ cat data.txt Line1 Line2 Line3 Line4 Line5 AMD$ grep -vxf lines.txt data.txt Line1 Line3 Line5 Print the lines that are not matching (-v) the exact lines (-x) from the file lines.txt (-f...

Missing one condition to display a string

shell

The 'grep' command uses a regular expression to match text. Use a '^' before the expression, to match from the start of the line. So, you can change the line name=$(echo $hello | cut -d' ' -f9 | grep $1) to name=$(echo $hello | cut -d' ' -f9 | grep...

How do I align my output?

shell

I'd rewrite that as: #!/bin/bash while read -ra hello; do name=${hello[8]} if [[ $name == "$1"* ]]; then log=${hello[2]} echo "$log $name" fi done | column -t read -ra splits the input line and stores the words in the "hello" array. [[ $name == "$1"* ]] is a built-in way...

Ignore first few lines and last few lines in a file Linux

linux,awk

awk cannot look ahead so you'll have to save the lines. awk 'NR>2{if(z!="")print z;z=y;y=x;x=$0}' file Practically zero memory overhead...

Delete some lines from text using Linux command

linux,shell,sed,grep,pattern-matching

The -v option to grep inverts the search, reporting only the lines that don't match the pattern. Since you know how to use grep to find the lines to be deleted, using grep -v and the same pattern will give you all the lines to be kept. You can write...

How to extract single-/multiline regex-matching items from an unpredictably formatted file and put each one in a single line into output file?

linux,shell,unix,replace,grep

Assuming that your document is well-formed, i.e. opening tags always match with a closing tag, then this may be what you need: sed '[email protected]<[/]\?b>@\n&\[email protected]' path/to/input.txt | awk 'BEGIN {buf=""} // {Y=1; buf=""} /<\/b>/ {Y=0; print buf""} Y {buf = buf$0} ' | tr -s ' ' Output: data1...

How can I resolve the “Could not fix timestamps in …” “…Error: The requested feature is not implemented.”

linux,build,f#

This is usually a sign that you should update your mono. Older mono versions have issues with their unzip implementation

Extra backslash when storing grep in a value

linux,bash

The output from set -x uses single quotes. So the outer double quotes were replaced with single quotes but you can't escape single quotes inside a single quoted string so when it then replaced the inner double quotes it needed, instead, to replace them with '\'' which ends the single...

Matching string inside file and returning result

regex,string,bash,shell,grep

Using sqlite3 from bash on OS X seems fairly straightforward (I'm no expert at this, by the way). You will need to find out which table you need. You can do this with an interactive session. I'll show you with the database you suggested: /Users/fredbloggs> sqlite3 ~/Library/Application\ Support/Dock/desktoppicture.db SQLite version...

fread(), solaris to unix portability and use of uninitialised values

c,linux,memory,stack,portability

Q 1. why is ch empty even after fread() assignment? (Most probably) because fread() failed. See the detailed answer below. Q 2.Is this a portability issue between Solaris and Linux? No, there is a possible issue with your code itself, which is correctly reported by valgrind. I cannot quite...

how to modify an array value with given index?

arrays,linux,bash

You don't need the quotes. Just use ${i}, or even $i: pomme[${i}]="" Or pomme[$i]="" ...

While loop in bash using variable from txt file

linux,bash,rhel

As indicated in the comments, you need to provide "something" to your while loop. The while construct is written in a way that will execute with a condition; if a file is given, it will proceed until the read exhausts. #!/bin/bash file=Sheetone.txt while IFS= read -r line do echo sh...

NASM: copying a pointer from a register to a buffer in .data

linux,assembly,nasm,x86-64

The problem is, you don't have debug info for the ptr type, so gdb treats it as integer. You can examine its real contents using: (gdb) x/a &ptr 0x600124 <ptr>: 0x7fffffffe950 (gdb) p/a $rsp $3 = 0x7fffffffe950 Of course I have a different value for rsp than you, but you...

Using an ad-hoc libc with a tool which is an argument of another tool

linux,shared-libraries

You can achieve that by using the env utility: timeout 10 /usr/bin/env LD_LIBRARY_PATH=/path/to/mod/libc/ cp a b Env will set the environment variable and exec the other utility with that environment....

Bash modify CSV to change a field

linux,bash,awk

Please save following awk script as awk.src: function date_str(val) { Y = substr(val,0,4); M = substr(val,5,2); D = substr(val,7,2); date = sprintf("%s-%s-%s",Y,M,D); return date; } function time_str(val) { h = substr(val,9,2); m = substr(val,11,2); s = substr(val,13,2); time = sprintf("%s:%s:%s",h,m,s); return time; } BEGIN { FS="|" } # ## MAIN...

make error during building webkitgtk

linux,makefile,cmake,make

as you see, in Edit1, you (make) try to run JavaScriptCore-4.0.gir instead of compile it with g-ir-compiler; I tried on my pc and my command is: cd /home/davide/src/webkitgtk-2.8.3/build/Source/JavaScriptCore && \ /usr/bin/g-ir-compiler /home/davide/src/webkitgtk-2.8.3/build/JavaScriptCore-4.0.gir \ -o /home/davide/src/webkitgtk-2.8.3/build/JavaScriptCore-4.0.typelib as a workaround, you cand edit: build/Source/JavaScriptCore/CMakeFiles/JavascriptCore-4-gir.dir/build here's the lines on my file (the last...

linux - running a process and tailing a file simultaneously

bash,shell,tail

I would simply start the tail in background and the python process in foreground. When the python process finishes you can kill the tail, like this: #!/bin/bash touch /tmp/out # Make sure that the file exists tail -f /tmp/out & pid=$! python test.py kill "$pid" ...

Use Unix Executable File to Run Shell Script and MPKG File

osx,shell,unix

The most common issue when handling variables containing paths of directories and files is the presence of special characters such as spaces. To handle those correctly, you should always quote the variables, using double quotes. Better code would therefor be: sudo sh "$path/join.sh" sudo sh "$path/join2.sh" It is also advised...

How does the kernel separate threads from processes

linux,multithreading,linux-kernel

Unlike Windows, Linux does not have an implementation of "threads" in the kernel. The kernel gives us what are sometimes called "lightweight processes", which are a generalization of the concepts of "processes" and "threads", and can be used to implement either. It may be confusing when you read kernel code...

sed and PHP tags

regex,linux,sed

.* is greedy: it matches all possible characters. This way, even sed 's/<?php.*//' file will also delete all the content in your file. To prevent this greediness of .*, say "everything but a ?" -> [^?]*: sed 's/<?php[^?]*?><?php[^?]*?>//' file Test $ cat a <?php echo 'first' ?><?php echo 'second' ?><?php...

How to test if a command is a shell reserved word?

bash,shell

#!/bin/bash string=$1 if [[ $(type "$string" 2>&1) == "$string is a shell"* ]]; then echo "Keyword $string is reserved by shell" fi ...

What does it indicate if /proc/PID/maps shows zero for all addresses?

linux,linux-kernel

I found the discussion in Valgrind mail list when someone had the same problem. The issue was that the kernel have been patched with PaX patches, one of which doesn't allow to look at the /proc/pid/maps. The quote about the patch from wikipedia The second and third classes of attacks...

AWK write to new column base on if else of other column

linux,bash,shell,awk,sed

You can use: awk -F, 'NR>1 {$0 = $0 FS (($4 >= 0.7) ? 1 : 0)} 1' test_file.csv ...

Git post-receive hook is not executed

linux,git,githooks,git-post-receive

The hook file is incorrectly named post-reveive.

linux running command as root from c code that run as normal user

c++,linux

A workaround is to modify the sudoers file and remove the requirement of a password from your user ID for a particular script to have sudo privileges. Enter sudo visudo After this, add the details in the following manner. username ALL=(ALL) NOPASSWD: /path/to/script Another method would be to pipe the...

Force linux to use php as php55

php,linux,fedora

You can create an alias: alias php="php55" Now if you type php it uses php55...

How to append entry the end of a multi-line entry using any of stream editors like sed or awk

linux,bash,awk,sed,sh

Here's a sed version: /^Host_Alias/{ # whenever we match Host_Alias at line start : /\\$/{N;b} # if backslash, append next line and repeat s/$/,host25/ # add the new host to end of line } If you need to add your new host to just one of the host aliases, adjust...

using sed to replace a line with back slashes in a shell script

regex,bash,shell,ssh,sed

You can use it with ssh and heredoc like this: ssh -t -t [email protected]<<'EOF' sed 's~out_prefix=orderid ^2\\\\d\\+ updatemtnotif/~out_prefix=orderid ^2\\\\d\\+ updatemtnotif_fr/~' ~/path/to/file exit EOF PS: It is important to quote the 'EOF' as shown....

Linux-wget command

linux,shell,wget

Try this to create a string variable n, with no leading whitespace (thanks @011c): n="10.0.0.135.527" wget http://infamvn:8081/nexus/content/groups/LDM_REPO_LIN64/com/infa/com.infa.products.ldm.ingestion.server.scala/"$n"-SNAPSHOT/com.infa.products.ldm.ingestion.server.scala-"$n"-20150622.210643-1-sources.jar ...

How to extract first letters of dashed separated words in a bash variable?

linux,string,bash,shell,variables

This isn't the shortest method, but it doesn't require any external processes. IFS=- read -a words <<< $MY_TEXT for word in "${words[@]}"; do MY_INITIALS+=${word:0:1}; done ...

shell script cut from variables

bash,shell,shellcode

With GNU grep: grep -oP 'aaa&\K.*' file Output: 123 456 \K: ignore everything before pattern matching and ignore pattern itself From man grep: -o, --only-matching Print only the matched (non-empty) parts of a matching line, with each such part on a separate output line. -P, --perl-regexp Interpret PATTERN as a...

Why can I view some Unix executable files in Mac OS X and not others?

git,bash,shell,unix,binary

Executable files may be scripts (in which case you can read the text), or binaries (which are ELF formatted machine code). Your shell script is a script; git is an ELF binary. You can use the file command to see more detail. For example, on my nearest Linux system: $...