Commands by SiegeX

Commands by SiegeX (5)

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Grep without having it show its own process in the results

The trick here is to use the brackets [ ] around any one of the characters of the grep string. This uses the fact that [?] is a character class of one letter and will be removed when parsed by the shell. This is useful when you want to parse the output of grep or use the return value in an if-statement without having its own process causing it to erroneously return TRUE. Show Sample Output
This is sample output - yours may be different.
```
$ ps aux | grep "crond"
root      2638  0.0  0.0   1912   640 ?        S     2008   0:10 /usr/sbin/crond -l10
siegex    6312  0.0  0.0   2084   636 pts/0    R+   19:42   0:00 grep crond

$ ps aux | grep "[c]rond"
root      2638  0.0  0.0   1912   640 ?        S     2008   0:10 /usr/sbin/crond -l10
```
12

ps aux | grep "[s]ome_text"

SiegeX · 2009-02-17 02:10:50 1
Recursively move folders/files and preserve their permissions and ownership perfectly
This is sample output - yours may be different.
2

cd /source/directory; tar cf - . | tar xf - -C /destination/directory

SiegeX · 2009-02-17 02:09:04 1
Use tee + process substitution to split STDOUT to multiple commands

Using process substitution, we can 'trick' tee into sending a command's STDOUT to an arbitrary number of commands. The last command (command4) in this example will get its input from the pipe. Show Sample Output
This is sample output - yours may be different.
```
$ echo foo | tee >(cat) >(cat) >(cat) | cat
foo
foo
foo
foo
```
23

some_command | tee >(command1) >(command2) >(command3) ... | command4

SiegeX · 2009-02-17 01:55:07 3
Parse a quoted .csv file

The $2, $3, $4 fields are arbitrary but note that the first field starts from $2 and the last field is $NF-1. This is due to the fact that the leading and trailing quotes are treated as field delimiters. Show Sample Output
This is sample output - yours may be different.
```
$ echo '"foo", "bar", "baz"' | awk -F'^"|", "|"$' '{ print $2,$3,$4 }'
$ foo bar baz
```
7

awk -F'^"|", "|"$' '{ print $2,$3,$4 }' file.csv

SiegeX · 2009-02-16 21:32:46 0
Convert Unix newlines to DOS newlines

The ctrl+v,ctrl+m portion represents key presses that you should do. If you do it successfully you should see a ^M character appear.
This is sample output - yours may be different.
4

sed 's/$/<ctrl+v><ctrl+m>/'

SiegeX · 2009-02-16 20:53:05 2

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Which processes are listening on a specific port (e.g. port 80)

swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

Banner Grabber

Convert a string to

Find inside files two different patterns in the same line and for matched files show number of matched lines

The option -print0 for find and -0 for grep help prevent issue with weird characters or spaces in filenames. Furthermore with xargs there is no limited number of arguments that find can throw.

connects to a serial console

e.g., 'screen -L /dev/ttyUSB0 38400' listens to your Holux M-241 GPS logger and turns on automatic logging

Get all these commands in a text file with description.

I tried out on my Mac, jot to generate sequence ( 0,25,50,..), you can use 'seq' if it is linux to generate numbers, need curl installed on the machine, then it rocks. @Satya

Debug how files are being accessed by a process

Instead of looking through `lsof` results, use inotifywait!

Which processes are listening on a specific port (e.g. port 80)

swap out "80" for your port of interest. Can use port number or named ports e.g. "http"

show git logging

shows some logging for the git repo.

find previously entered commands

Searches bash-history in reverse order (last entered commands first). Pressing ctrl+r again shows the next matching entry.

Stay in the loop…

Follow the Tweets.

Every new command is wrapped in a tweet and posted to Twitter. Following the stream is a great way of staying abreast of the latest commands. For the more discerning, there are Twitter accounts for commands that get a minimum of 3 and 10 votes - that way only the great commands get tweeted.

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