Easy and direct way to find this out. Show Sample Output
Curious about differences between /bin, /usr/bin, and /usr/local/bin? What should be in the /sbin dir? Try this command to find out. Tested against Red Hat & OS X
I find this terribly useful for grepping through a file, looking for just a block of text. There's "grep -A # pattern file.txt" to see a specific number of lines following your pattern, but what if you want to see the whole block? Say, the output of "dmidecode" (as root):
dmidecode | awk '/Battery/,/^$/'
Will show me everything following the battery block up to the next block of text. Again, I find this extremely useful when I want to see whole blocks of text based on a pattern, and I don't care to see the rest of the data in output. This could be used against the '/etc/securetty/user' file on Unix to find the block of a specific user. It could be used against VirtualHosts or Directories on Apache to find specific definitions. The scenarios go on for any text formatted in a block fashion. Very handy.
Using awk, find duplicates in a file without sorting, which reorders the contents. awk will not reorder them, and still find and remove duplicates which you can then redirect into another file.
This dup finder saves time by comparing size first, then md5sum, it doesn't delete anything, just lists them.
As an alternative to using an additional grep -v grep you can use a simple regular expression in the search pattern (first letter is something out of the single letter list ;-)) to drop the grep command itself. Show Sample Output
Find random strings within /dev/urandom. Using grep filter to just Alphanumeric characters, and then print the first 30 and remove all the line feeds. Show Sample Output
I did not know this, i'd like to share...
If you enable multiuser, then you can permit others to share your screen session. The following conditions apply: 1. screen must be suid root; 2. "multiuser on" must be configured in ~/.screenrc; 3. control the others user(s) access with "aclchg": # ----- from ~/.screenrc-users ----- aclchg someuser +rx "#?" #enable r/o access to "someuser" aclchg someuser -x "#,at,aclchg,acladd,acldel,quit" # don't allow these aclchg otheruser +rwx "#?" # enable r/w access to "otheruser" aclchg otheruser -x "#,at,aclchg,acladd,acldel,quit" # don't allow them to use these commands # ----- After doing this (once), you start your session with: $ screen Then, the other user can join your terminal session(s) with youruserid: $ screen -r youruserid/ Note: the trailing "/" is required. Multiple users can share the same screen simultaneously, each with independent access controlled precisely with "aclchg" in the ~/.screenrc file. I use the following setup: # ~/.screenrc-base # default screenrc on any host source $HOME/.screenrc-base source $HOME/.screenrc-$HOST source $HOME/.screenrc-users # ----- Then, the base configurations are in ~/.screenrc-base; the host-specific configurations are in ~/.screenrc-$HOST, and the user configurations are in ~/.screenrc-users. The host-specific .screenrc file might contain some host-specific screen commands; e.g.: # ~/.screen-myhost # ----- screen -t 'anywhere' /bin/tcsh screen -t 'anywhere1' /bin/tcsh # ---- The .screenrc-base contains: # ~/.screenrc-base ## I find typing ^a (Control-a) awkward. So I set the escape key to CTRL-j instead of a. escape ^Jj termcapinfo xterm* ti@:te@: autodetach on zombie kr verbose on multiuser on
This uses Bash's "process substitution" feature to compare (using diff) the output of two different process pipelines.
Useful mainly for debugging or troubleshooting an application or system, such as X11, Apache, Bind, DHCP and others. Another useful switch that can be combined with -mmin, -mtime and so forth is -daystart. For example, to find files that were modified in the /etc directory only yesterday:
sudo find /etc -daystart -mtime 1 -type f
Ever ask yourself "How much data would be lost if I pressed the reset button?" Scary, isn't it? Show Sample Output
I have a bash alias for this command line and find it useful for searching C code for error messages. The -H tells grep to print the filename. you can omit the -i to match the case exactly or keep the -i for case-insensitive matching. This find command find all .c and .h files Show Sample Output
Write a file you edited in Vim but that you do not have the permissions to write to (unless you use sudo.) Same as #1204 but without the echo to stdout that I find annoying.
Find files in a specific date range - in this case, the first half of last year.
-newermt = modification time of the file is more recent than this date
GNU find allows any date specfication that GNU date would accept, e.g.
find . -type f -newermt "3 years ago" ! -newermt "2 years ago"
or
find . -type f -newermt "last monday"
sorts the files by integer megabytes, which should be enough to (interactively) find the space wasters. Now you can
dush
for the above output,
dush -n 3
for only the 3 biggest files and so on. It's always a good idea to have this line in your .profile or .bashrc
Show Sample Output
This command is more portable than it's cousin netstat. It works well on all the BSDs, GNU/Linux, AIX and Mac OS X. You won't find lsof by default on Solaris or HPUX by default, but packages exist around the web for installation, if needed, and the command works as shown. This is the most portable command I can find that lists listening ports and their associated pid. Show Sample Output
I often use it to find recently added ou removed device, or using find in /dev, or anything similar. Just run the command, plug the device, and wait to see him and only him Show Sample Output
You got some results in two variables within your shell script and would like to find the differences? Changes in process lists, reworked file contents, ... . No need to write to temporary files. You can use all the diff parameters you'll need. Maybe anything like $ grep "^>" is helpful afterwards.
Use this command to find out a list of committers sorted by the frequency of commits. Show Sample Output
Compress information DBs of firefox to speed up the launch of browser.
I save this to bin/iptrace and run "iptrace ipaddress" to get the Country, City and State of an ip address using the http://ipadress.com service. I add the following to my script to get a tinyurl of the map as well: URL=`lynx -dump http://www.ip-adress.com/ip_tracer/?QRY=$1|grep details|awk '{print $2}'` lynx -dump http://tinyurl.com/create.php?url=$URL|grep tinyurl|grep "19. http"|awk '{print $2}'
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