Arithmetic Substitution

->VAR=$(( 1+3*2 ))
->echo $VAR
7

->VAR=$(( (1+3)*2 ))
->echo $VAR
8

Filename Substitution with Wildcards

Wildcards
*  0 or more characters
?  1 character
 

Command typed	Meaning
ls *	display all files
ls *.sh	display all shell scripts
ls go*	display all files starting with the letters 'go' and any possible combination of other characters afterwards
ls go??	display all files starting with 'go' and two unknown characters
ls go[abcd]	display all files starting with 'go' and one more character of either 'a', 'b', 'c', or 'd'
ls go[a-d]	display all files starting with 'go' and one more character in the 'a' to 'd' range
ls go[a-dA-D]	display all files starting with 'go' and one more character in the 'a' to 'd' range or the 'A' to 'D' range
ls go[!a-d]	display all files starting with 'go' and one more character not in the 'a' to 'd' range
ls [a-d]*	display all files starting with 'a', 'b', 'c', and 'd' and any other character -- or no other characters

All About Variables

Format

VARIABLE_NAME = value

echo $VARIABLE_NAME  

Types

• scalar variable -- holds 1 value at a time (aka name value pairs)
• array variable -- holds 0 or more values

Variable Names

• a-z, 0-9 or underscore
• conventionally uppercase
• start with letter

Setting Values

PET=fish

PET='fish bowl'

PET="fish bowl"

Setting Scalar Values

->PET= cat #A space will cause an error

ksh: cat:  not found

->PET=cat

->echo $PET

cat

->pet='cat fish'

->echo $pet

cat fish

->PET=ferret

->echo $pet   # $pet is not the same as $PET

cat fish  

->echo $PET

ferret

Setting Array Values

->PET[1]=FERRET

->PET[2]=parrot

->echo ${PET[1]}

FERRET

->echo ${PET[2]}

parrot

->echo ${PET[0]}# set since name is same as scalar variable

ferret

Set Variables to Read-only

->readonly PET # now PET can't be set to a value

->PET=dog

ksh: PET: is read only

Unset Variables (if not readonly)

->TREE=oak

->echo $TREE

oak

->unset TREE

->echo $TREE

Variable Types

  local

available within the current instance. not available to programs started by the shell

  environment

variable available to child processes Use export to create an environmental variable from a local variable                         export VARIABLE=value

  shell

special variables set by the shell

Miscellaneous Unix Commands

type two commands at a time	cmd1 ; cmd2
spell check a file	cat filename | spell
Reset terminal: if mistakenly viewed a binary file with cat	stty sane
append results of a command onto an existing file	cmd>>file.ext
write results of a command to a file	cmd>file.ext
logout	[Ctrl]+D or exit
ftp file to host1 from host2	ftp host1
search files for a string -# = display '#' lines on both sides -c = display a count -v = display non-matching lines -i = ignore case	grep string filename

View File Content

view file contents	more file.ext
view last 10 lines of a file	tail filename
view multiple files	head filenam* | more
view top # lines of a file	head -# filename
view top 10 lines of a file	head filename

Sort

sort file	sort filein > fileout
sort file and remove duplicates	sort filein > fileout | uniq
sort file and view duplicates	sort filein > fileout | uniq -d
sort file numerically	sort -n filein > fileout
sort multiple files together	sort filein1 filein2 > fileout

System Information

list current shell	echo $SHELL
show your group	grep yourid /etc/passwd
show all groups	more /etc/group
system information	uname -a
who's logged in	finger

Help: Man Pages

help : output to a file in home directory for further annotation	man cmd | col -b > ~/file.ext
help : viewing a specific page #	man -s # cmd
help (on-line)	man cmd
help with index	man -k cmd

Find Files

find files from current directory down	find . -name filename
find files from home directory using wildcards	find ~ -name filenam*

Directory Listing

show subdirectory	pwd
list files and directories	ls
list files and directories (one per line)	ls -l
list files beginning with 'Adams'	ls adams*
list files by screenful	ls | more

Delete Files

delete files with prompting

rm existingfile

Counts

count files in a directory	ls | wc -l filename
count lines files	wc -l filename
count lines words and bytes	wc filename
count words files	wc -w filename
write a file count to a file	ls | wc -l > file.ext

Copy / Move

concatenate files together in new file	cat oldfile1.ext oldfile2.ext > bothfiles.ext
copy a file and prompt before overwriting	cp -i existingfile newfile
copy top # lines of a file to a new file	head -# filename > newfilename
move a file and prompt before overwriting	mv -i existingfile newfile

Compare Files and Directories

compare two directories	diff /directory1 /directory2
compare two files	cmp file1 file2
compare two files and show specific differences-i=ignore case-b=ignore blanks-w=ignore spaces and tabs	diff -iwb file1 file2
compare two files side-by-side| lines are the same< line is in first file only> line is in second file only	sdiff file1 file2
compare two files side-by-side showing only differences	sdiff -s file1 file2

Change / Make Directory

make a directory	mkdir subdir
change to a subdirectory beneath where you are	cd subdir
change to a subdirectory of the root	cd /subdir
change to a subdirectory under your home directory	cd ~/subdir
change to home directory	cd
change up one level	cd ..

Permissions

add write access to current permissions for a file	chmod g+w filename
remove all access for this directory and subdirectories	chmod -r go-rwx *
remove write access from everyone but you	chmod go-w filename
replace current permissions for a file with those specifiedu=user, g=group, o=othersr=read, w=write, x=execute	chmod u=rwx,g=rwx,o=rwx filename
change group associated with files	chgrp newgroup filename
add all permissions for everyone	chmod 777 filename
change ownership of files	chown newowner filename

Just Some Miscellaneous Notes

Man / More / Less

[Spacebar]  view next screen
[Enter]      view a line at a time
b            view previous screen
q                    quit viewing

Naming Files

The system will allow a file to be created with the same name as a directory.

The system will allow a space in a name, but some programs have trouble with it.

Use periods or underscores to separate characters.

Documenting a Unix Script

#! /usr/bin/ksh
echo "# +-----------------------------------------------------------------------"
echo "# | Program ID:    scriptname.sh"
echo "# |"
echo "# | Purpose:       description"
echo "# |"
echo "# | Developer:     Lynn Tobias"
echo "# | Program Date:  mm/dd/yyyy"
echo "# |"
echo "# | Input File(s): /ux123/scripts/YES              -- 'Y' for prompts"
echo "# |                /ux123/scripts/ods_uat.password -- sql+ password"
echo "# |"
echo "# | Table(s) Used: EXT_BLDLIST"
echo "# |"
echo "# | Called by:     ?"
echo "# | Calls:         scriptname.pl"
echo "# |"
echo "# | Output:        /ux123/scripts/blddist.file10"
echo "# |                "
echo "# | Revisions:     Dvlpr Date     Version Comment/Change"
echo "# |                ----- -------- ------- --------------------------------"
echo "# |"
echo "# +-----------------------------------------------------------------------"

SQLPlus in a Here Document

This is called a 'here document' - because it says "here is the text for your input". The redirection expressed as "<<EOF" says "take what follows as though I typed it at the keyboard, until you find a token to match EOF as the first token on a line". The token EOF has no special meaning - it's just a string of characters used as a marker to tell the 'here document' when the text input is completed.

sqlplus <<EOF

      Select something

       from somewhere;

EOF

Important: the ending token must appear as the first characters on a line by itself.

Thanks to Jim Benz of Pittsburgh for these notes.

Password Variables

#! /usr/bin/ksh

echo "#------------------------------------------------------------------------------"
echo "# get passwords for the ftp and for sqlplus and assign to variables."
echo "#------------------------------------------------------------------------------"

export FTP_PASS='cat /ux123/dfact/xlt/scripts/ust_grp.password'

export SQL_PASS='cat /ux123/dfact/xlt/scripts/xlt_ods_uat.password'

echo "#------------------------------------------------------------------------------"
echo "# start ftp from vax --i: turn off prompting    n: turn off login"
echo "#------------------------------------------------------------------------------"

ftp -in host1 <
quote user ust_grp
quote pass $FTP_PASS
...
quit
EOF

echo "#------------------------------------------------------------------------------"
echo "# In SQL+, ...
echo "#------------------------------------------------------------------------------"

sqlplus -s  $SQL_PASS << EOF
.
.
exit;
EOF

Directory Listing

Grep

match any character	.	grep l..n filename	finds 'lynn' or 'loan'
match only if at the beginning of a line	^	grep ^day filename	finds 'day into night'but not 'Some day'
match only if at the end of the line	$	grep day$ filename	finds 'One fine day'but not 'Monday is good'
search for '.' or '^' or '$' in a file	\	grep \* filename	finds '*****1.05'
search for a set of names	[]	grep [dog,dil]bert filename	finds 'dogbert' and 'dilbert'
find all lines that start with an alphabetic character in upper or lower case	^[]	grep ^[A-Z,a-z] filename