UNIX Slightly Longer Reference Guide (still for newbies)


Shell Directories Files Archiving Processes Network Misc

The BASH Shell
exit exit the shell; log you out if it is the login shell
bash start the bash shell (in a subshell)
echo [opt] [string] display a line of text. Note: this is built-in to most shells, so will vary. (POSIX):
opt:
-n suppress newline
-e enable backslash characters (\n, \t, \a, \f, ...)
-E disable interpretation of backslash characters

EXAMPLES
echo Is this a star *?
echo "This is a star *"
echo "This is my userid: $USER"
echo 'This is my userid: $USER'
echo "Today is `date`"
command > file redirects the output (stdout) from command to file.
EXAMPLE
  ls -1 > fileList
command < file redirects the input (stdin) to command from file.
EXAMPLE
  mail -s "Can't get any sleep" DearAbbey@ap.com < myWifeSnores.txt
command1 | command2 output (stdout) from command1 is piped to the stdin of command2.
EXAMPLEs
  ls -a | more
  ls -l /tmp | grep kschmidt | awk '{print $9}'
Filesystem / Directories
ls [opt] [dir] lists contents of dir (current dir. by default)
opt:
-aall
-Ccolumns
-Fformat
-llong
pwd print working directory. Shows you the current (working) directory.
cd [dir] change directory to dir (user's home by default)
mkdir [-p] dirname make directory.  Creates dirname.
-pmake parent directories, as needed
rmdir dirname remove directory.  Removes dirname
cp [opt] src targ
cp [opt] src... dir
copies src to targ, or copy src(s) to dir.
opt:
-iinteractive if targ exists, prompt user before overwriting
-ppreserve file attributes, where possible
-Rcopy directories recursively
mv [opt] src target
mv [opt] src... dir
renames src to targ, or move src(s) to dir.
opt:
-iinteractive if targ exists, prompt user before overwriting
rm [opt] targ.. deletes (removes) targ(s).
opt:
-iinteractive prompt user before actually unlinking each file
-rrecursive (careful!)
-fforce
Files
cat [file].. displays (catalogs) the contents of file(s) (stdin by default).
more [file].. displays file(s) (stdin by default) one screen at a time
less enhanced version of more. Not available everywhere
vi the standard UNIX text editor.  Know it
head -n cnt [file].. Prints the first cnt (default 10) lines of file(s) (default stdin)
tail -n cnt [file].. Prints the last cnt (default 10) lines of file(s) (default stdin)
wc [opt] [file].. word count Reports on number of lines, characters, and words in a file(s) (default stdin).
opt:
-c# of bytes
-m# of chars (same, if ASCII text file)
-l# of newlines
-Llength of longest line
-w# of words
grep pattern [file]... Searches file(s) (stdin) for pattern (a regular expression). Prints matching line, by default. Again, there are different greps out there, so not all options available (-q, -r).
opt:
-cjust print a count of matching lines
-iignore case
-nprefix output w/line numbers
-qquiet; no output (just return 0 if match is found)
-rrecursive; read files under listed directories
find path [opt] Searches subtree rooted at path, prints filenames that pass all subsequent tests (left to right) listed in opt.
opt:
Numeric args can be specified as:
+ngreater than n
nexactly n
-nless than n
Tests:
-mtime n modified n * 24 hours ago
-name pattern name matches pattern (be careful to quote, if using wildcards)
-inamelike -name, but case insensitive
-size n file used n * 512 bytes
-type c if file is of type c, where c is one of d, f, and l, for directory, regular file, and symbolic link, respectively (partial list)
Actions
-exec command ; execute command; true if 0 is returned. {} is replaced by current filename
-printtrue; prints filename to stdout

EXAMPLES
Find all files in current subtree that have "resume" in the name:
  find . -iname "*resume*" -print
Find all files in my mail directory that mention "motorcycle":
  find ~/mail -exec grep -iq motorcycle {} \; -print
Find all regular files in my Web directory modified in the past 2 days:
  find ~/public_html -type f -mtime -2 -print

sort [opt] [file].. sorts file(s) (default stdin), to stdout. See man pages.
opt:
-fignore case (fold lower to upper)
-kp1,[p2] fields to sort, left to right
-mmerge already sorted files
-ncompare in numerical sense
-rreverse; sort in descending order
Archiving
tar oper [opt] [file]... Tape ARchive to create or restore archives. Makes many files into one, or vise versa. Note, the form of the options is changing, as is default behavior. Do a man, or info.
oper is one of:
c create
x extract
t table of contents

opt:
f filename the name of the archive (default is the tape). Use '-' for stdin/stdout
v verbose
z read or write through gzip (Linux only)

EXAMPLES
To archive all contents of current directory to file backup.tar:
  tar cvf backup.tar *
To extract some archive on the floppy to the current directory:
  tar xvf /mnt/floppy/backup.tar
To archive and gzip all of your public_html files to ~/web.tgz:
  tar cvf - ~/public_html | gzip > ~/web.tgz   , or:
  tar czvf ~/web.tgz ~/public_html (where available)
To extract a gzipped tar file:
  gunzip -c back.tar.gz | tar xvf -   , or:
  tar xvzf back.tar.gz (where available)

gzip, gunzip [file].. To compress and decompress file(s) (not the compress utility). Adds or looks for .gz extension, by default. See man pages.
opt:
-c to stdout

NOTE
If input is stdin, then output is to stdout

unzip Decompresses DOS Zip files (made by PKWare)
Processes
ps [opt] process status. Reports on processes.
opt:
-eall users
-ffull listing (more info)
-Fformat
-llong
kill [opt] pid Send signals to a process with ID pid.
opt:
-9SIGKILL (The one to kill a process, and its children.)
-15SIGTERM (A bit nicer, asks a process to end.)
Network
ssh userId@host Provides a terminal i/f, much like telnet, but secure
scp [userId@host:]src [userId@host:]targ Secure copy. Copies between computers, encrypted
ssh-keygen, ssh-copy-id Create keys, copy them to distant host, skip the password
rsync [options] [userId@host:]src [userId@host:]targ Used for syncing directories between machines. Way handy.

EXAMPLES
To pull/sync down the directory from tux to local:
rsync -avuz userID@tux:CS265/Lab1 .
To pull/sync down the files in the directory from tux to local:
rsync -avuz userID@tux:CS265/Lab1/ .
To push them back up, by directory:
rsync -avuz Lab1 userID@tux:CS265/

mail The standard UNIX mail reader. Don't bother
mutt A nice CLI mail reader, understands MIME and UUEncode types
Misc. Unix
man [sect] [-k keyword] item man pages.  Displays help on item, in sect.
opt:
-kkeyword. Search entries for keyword.

This collection is, by far, incomplete.  Just a quick and dirty list to get going, for budding programmers new to Unix.  If you think of something that should really be in here (or see any errors), please let me know: kschmidt@cs.drexel.edu