Recently I lost a number of changes I made to a program when the SCO Unix system went down. The system "mail" suggested a "vi -r" option that took me back several days. To prevent this in the future, I am trying to create my own vi command:
Code:
if [ $# -eq 1 ]
then
cp -p $1 $1.bak
fi
/usr/bin/vi $*
if [ $# -eq 1 ]
then
rm $1.bak
fi
I put this in my home directory where my PATH in ".profile" is
I'm not sure what you think a PATH variable does. If a file has execute permissions (meaning you can run it by just typing the correct name of the file) then it can be run by typing the whole filename from anywhere
Code:
# example:
/path/to/shell.sh parameter1
This is awkward if you have your current directory somewhere else. So. PATH allows you to put directories into the variable. Then when you type the name no matter where your current directory is set, the PATH looks up the file, then lets you run it.
Example after adding the directory where shell.sh lives to PATH:
Code:
shell.sh parameter1
Not delete it
Not write to it.
Just execute it.
The which command helps you figure out what file you will execute before you try to run it. Why? Well, in the example: shell.sh could be in several places. So if you type shell.sh you could be running another script by accident. PATH can be a cause of this.
Code:
export PATH=".:${PATH}"
makes the current directory part of the PATH. Dangerous.
Example: I use t.shl as a throwaway temporary filename. So it could be in any of the my own directories.
Code:
which t.shl
tells me which one will run when I type the command.
Last edited by jim mcnamara; 07-26-2018 at 10:37 PM..
$@ muist be in quotes. Unquoted it will expand like $*
Code:
$ cat demo
echo '$@ - word splitting takes place'
for f in $@
do
echo "$f"
done
echo '"$@" - quotes prevent word splitting; $@ (and [@] in arrays in later shells) split into arguments (elements) nevertheless'
for f in "$@"
do
echo "$f"
done
$ /bin/sh demo "" 1 2 "3 4"
$@ - word splitting takes place
1
2
3
4
"$@" - quotes prevent word splitting; $@ (and [@] in arrays in later shells split into arguments (elements) nevertheless
1
2
3 4
As a last exercise try
Code:
/bin/sh demo "*"
You see that unquoted the shell does a glob-expansion against the current directory. (That you can prevent with set -f)
if [ $# -eq 1 -a -s $1 ]
then
cp -p $1 $1.bak
echo "While using vi, $1.bak has been created."
sleep 1
fi
/usr/bin/vi $*
if [ -f $1.bak ]
then
rm $1.bak
fi
I realize vi can edit a number of files, start at a specific position, or after a search, but we seldom use any extra bells or whistles. Near the end of a Y2K conversion script, a vi searched for "-YEAR" in the command line, but that was 19 years ago.
Thanks for looking at it, I might revisit this thread and check for new ideas in the near future.
For the sake of not going insane and not buggering a load of needed system stuff, I have created a dir /mybin. (This is a Debian system.)
I have then edited the /etc/profile and /etc/login.defs files and added :/mybin to all of the path variables. I have the file /mybin/mtp for... (2 Replies)
Hi all,
I have a variable test has the following value assigned.. could you please help on doing cd or ls to the value in the varible ...
$echo $test
/bdm/sdd/compounds/AD4833XT/requests/clin/Watson_20090420/docs/MHRA\ Comments\ \&\ Responses
$cd $test
ksh: cd: bad argument count
$cd... (3 Replies)
Hi I am using MKS Toolkit c shell.
I want to basically check if my PATH variable already contains a certain path directory so I tried this (it didnt work!): if: Expression Syntax
if ( echo $path |grep -c c:/PROGRA~1/blah/blah ) then
please help me get this little statement to work.
... (3 Replies)
On one of the machines at work, we had Net-SNMP 5.2.3 installed, and I wanted to upgrade that to 5.4.2.1. So I downloaded the tar file, extracted it, did the configure, make, make test, make install, and everything worked.
All the executable files (like snmpget, snmpset, snmpwalk) got copied to... (1 Reply)
I am trying to install the pkg-get package to a fresh install of Solaris 10. I am able to download and install correctly using the default directory for both pkg-get and wget as found on blastwave.org. When I issue the command "which wget and which pkg-get" it returns no wget or pkg-get found in... (1 Reply)
How to pass a file path to open a file?
I am using cygwin.
I want to open a file from a particular path, say C:\Test\File1,. This file path is stored in a variable.
I am able to cat a file like this :
cat "c:\Test\File1"
but i want the same thing to happen in my script file through a variable... (3 Replies)
Hi
i am writing a script containing processing commands which are reside in /opt/terascan/bin dir. if i run the script from command prompt it is working fine. but in crontab it is not working.
if i give env command from command prompt it is showing /opt/terascan/bin dir in PATH variable.
... (10 Replies)
hi ,
i have written csh script i am unable to set PATH variable in my script.
my script is like this
=====================================
# ! /bin/csh -f
setenv PATH "$PATH:/opt/terascan/bin"
ls -l > list
lspass > pas
peekauto > schedule \
num_days = 1 \
exit 0... (1 Reply)
Hello everyone,
I'm a unix noob. I have a powerbook running mac os x 10.4 and for one of my classes I need to install the latest version of php (5.0.5). I'm following the instructions at http://developer.apple.com/internet/opensource/php.html to install but I've run into a problem.
The... (2 Replies)