Linux Commands

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Revision as of 01:40, 9 December 2008 by Mip (talk | contribs) (→‎grep: --only-matching)
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dd

Convert and copy a file.

dd returns current copy status when sent an HUP signal. Type in another shell: 

while :; sleep 5; do killall -s SIGHUP1 dd; done

This will force dd to update its status every 5sec.

dpkg

Package manager for Debian / Ubuntu. See Package Management#Ubuntu / Debian

echo

echo -e "Some text\n...on 2 lines..."                    # Enable interpretation of backslash escapes (must be quoted!)

find

find . -exec echo '{}' \;                                #semi-colon must be escaped!
find . -exec echo one '{}' \; -exec echo two '{}' \;     #to execute several commands on one match

grep

grep -Rsl PATTERN [FILE]            # Recursive, no error output, only list filename
grep BASIC-REG-EXP-PATTERN [FILE]   # Use classic regexp (like "dma\|DMA")
egrep EXT-REG-EXP-PATTERN [FILE]    # Same as grep -E. Use extended regexp (like "dma|DMA")
fgrep FIXED-STRINGS-REG-EXP [FILE]  # Same as grep -F. Pattern is a list of strings to match.
grep -n PATTERN [FILE]              # Print matched line numbers.
grep -- "-s" [FILE]                 # Search for text "-s"
grep -e "-s" [FILE]                 # Search for text "-s" - alternative solution
grep -R -include=*.in PATTERN *     # Search recursively through folders, limiting to files matching pattern "*.in"
grep -R PATTERN *.in                # Idem, but matching pattern "*.in" also applies to folders.
grep -o PATTERN [FILE]              # (--only-matching) Print only the matched (non-empty) parts of a matching line.

multitee

multitee sends multiple inputs to multiple outputs.
Check this page.
Original is here, or can also be found here on Debian.

Here a patch to build it on Cygwin. The patch ports calls to BSD signal.h API (struct sigvec, sigvec(), sigmask(), sigblock()...) to the POSIX API (struct sigaction, sigaction(), sigprocmask(), sigfillset()...): 

$ patch -Np1 <../multitee-3.0-cygwin.patch
$ make
$ cp multitee.1 /usr/local/man/man1
$ cp multitee.exe /usr/local/bin

Example of use: 

$ multitee 0-1,4,5 4> foo 5> bar             # same as tee foo bar with better blocking behavior
$ multitee 0:1 3:1 4:1,2 6:7                 # various merge and copy
$ tcpclient server smtp multitee 0:7 6:1e0   # e0 tell multitee to quit as soon connection close
$ multitee 0:3 3:1                           # same as 'socat - FD:3'

netcat

TCP-IP swiss army knife (equivalent of the telnet program. Check wikipedia:netcat. Also known as command nc).

netstat

Print network connections, routing tables, interface statistics, masqurade connections, and multicast memberships 

netstat -atpn      #All, tcp, socket program PID, numeric
netstat -rn        #Kernel route table, numberic

When listing sockets (default output), you'll get an output like: 

% netstat -at

Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 *:time                  *:*                     LISTEN
tcp        0      0 localhost:mysql         *:*                     LISTEN
tcp        0      0 andLinux.local:43449    windows-host:x11        ESTABLISHED

% netstat -atn

Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address           Foreign Address         State
tcp        0      0 0.0.0.0:37              0.0.0.0:*               LISTEN
tcp        0      0 127.0.0.1:3306          0.0.0.0:*               LISTEN
tcp        0      0 192.168.11.150:43449    192.168.11.1:6000       ESTABLISHED
Local Address
* or 0.0.0.0 means that the process accepts connection from any interface.
127.0.0.1 means it only accepts connection on localhost loopback (and so only connection that originates from local PC as well).
Any other IP address means that the process listen on the given port at the given IP address

recode

recode /cl../cr <dos.txt >mac.txt
recode /cr.. <mac.txt >unix.txt
recode ../cl <unix.txt >dos.txt
recode charset1/surface1..charset2/surface2 <input.txt >output.txt
recode /QP.. <qp.txt >normal.txt                                    # To convert quoted-printable text
charset surface
us ASCII (7 bits) /cr Carriage return as end of line (Mac text)
l1 ISO Latin-1 (ISO-8859-1, Western Europe, 8 bits) /cl Carriage return line feed as end of line (DOS text)
EUCJP EUC-JP for Japanese (Unix) / Line feed as end of line (Unix text)
SJIS Shift-JIS for Japanese (Microsoft) /d1 Human readable bytewise decimal dump
ISO2022JP Mail encoding for Japanese (7 bits) /x1 Human readable bytewise hexidecimal dump
u2 UCS-2 (Universal Character Set, 2 bytes) /64 Base64 encoded text
u8 UTF-8 (Universal Transformation Format, 8 bits) /QP Quoted-Printable encoded text

rpm

See Package Management#RPM's

sed

References

Usage

Some basic usage: 

sed [OPTION]... {script-only-if-no-other-script} [input-file]...
sed -n                              # Silent - suppress automatic printing of pattern space
sed -r                              # Use extended regular expression
sed -i "s/foo/bar/" *.txt           # In-place file modification

Use of address commands a\text, i\text, c\text. The command is terminated by a *newline*. To insert a newline character, use \n: 

$ cat mytext
First line
Second line
$ cat mysedscript
1 {i\inserted text
s/$/ (not anymore)/g}
$ sed -f mysedscript mytext
inserted text
First line (not anymore)
Second line

# All on one line: use echo -e to generate the newline that terminates the command i\
$ echo -e "1 {i\\inserted text\ns/$/ (not anymore)/g}"| sed -f - mytext
inserted text
First line (not anymore)
Second line

#Same result without command \i:
$ sed "1 {s/^/inserted text\n/; s/$/ (not anymore)/}" mytext

Regular expressions

The information below is only illustrative. See e.g. Wikipedia page for reference information. The list below is actually for extended regular expressions, which can be obtained in sed using option -r (sed -r).

Regexp Description
. Match any character
gray|grey Match gray or grey
gr(a|e)y Match gray or grey
gr[ae]y Match gray or grey
file[^0-2] Match file3 or file4, but not file0, file1, file2.
colou?r (zero or one) - Match Color or Colour.
ab*c (zero or more) - Match ac, abc, abbc, ....
ab+c (one or more) - Match abc, abbc, abbbc, ....
a{3,5} (at least m and not more than n times) - Match aaa, aaaa, aaaaa.
^on single line$ (start and end of line) - Match on single line on a single line.

When using standard (non-extended) regular expression, some special meta-characters (like the parenthesis ( ), or braces { }) must be quoted with backslash \.

socat

Command-line utility that establishes two bidirectional byte streams and transfers data between them ([1]). socat is the more powerful version of netcat. Check the homepage. 

socat -ly 'TCP4-LISTEN:143,reuseaddr,fork' PROXY:ton.imap.server:143|TCP:134.27.168.36:8080
ProxyCommand socat - 'PROXY:%h:%p,proxyauth=user:pass|SSL,verify=0|PROXY:my.server:443,proxyauth=user:pass|TCP:big.brother.proxy:8080'     # Using v2.0.0 beta

socat can be easily used as a replacement of telnet: 

socat tcp:<host>:<port> -       # <port> can be a port number or service name (telnet,imap...)

Some useful command-line options: 

socat -ly                       # Writes messages to syslog instead of stderr; severity as defined with option -d
socat -v                        # Writes the transferred data to their target stream but also to stderr (text mode)

Miscellaneous

htop
an improved top command
iconv
locale encoding conversions
konwert
fancy encoding conversions
mimencode
binary file conversion for the mail.;mkfifo
make FIFOs (named pipes)
pv, pipeview, pipebench
monitor the progress of data through a pipe
reformime
MIME E-mail reformatting tool
stat
display file or file system status
strace
trace system calls and signals
tee
read from standard input and write to standard output and files
tree
List the contents of directories in a tree-like format.
uuencode, uudecode
binary file conversion for Unix.
watch
Execute a program periodically, showing output full screen
xclip
xclip is a command line interface to the X11 clipboard. It can also be used for copying files, as an alternative to sftp/scp, thus avoiding password prompts when X11 forwarding has already been setup. Check this guide.
XSel
XSel is a command-line program for getting and setting the contents of the X selection (aka clipboard). Normally this is only accessible by manually highlighting information and pasting it with the middle mouse button.
xselection
Another package similar to xsel. But I can't get it work correctly on OpenSUSE...
xxd
Make a hexdump or do the reverse
$ echo 202122 | xxd -r -ps -                 # To decode a hexdump string
$ echo ' !"' | xxd -u -ps -                  # to code as a hexdump string (uppercase)
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