1. Because the PATH variable defines the directories your shell looks in for commands you type that aren't built into the shell. For instance if you type ls, and ls isn't an internal shell command, it looks through the directories in PATH for an executable file with the same name as the command you typed and tries to execure it. /bin and /usr/bin are used to store commonly used executable files such as ls, grep, chmod, etc.
2. Because the `` quotes are command substitution quotes. the shell will execute the command between them and then substitute is ouput in place of `command` as if you had typed it. `date` tries to run a command named whatever date outputs on your system.
3. Its easiest to use three seperate commands. If it takes longer to figure out how to do something in one command than it takes to type 3 and computing resources aren't an issue because you are only going to do it once or you have a tiny amount of data, why waste your time trying to figure out how to make a complex command work?
4. ${d-*} means if d is unset then assign * to d. see the parameter expansion section of the ksh, sh, or bash man page for more info.
5. yes
why are you doing his homework in full ?
This User Gave Thanks to ghostdog74 For This Post:
1. You have a very large file, named 'ColMe', tab-delimited, you are asked to process. You are told that each line in 'ColMe' has 7 columns, and that the values in the 5th column are integers. Using shell functions (and standard LINUX/UNIX filters), indicate how you would verify that these... (1 Reply)
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1. The problem statement, all variables and given/known data:
Hello,
My name is Jordan and studying at the New Bulgarian University in Sofiya. This is my homework but can... (2 Replies)
1. Write a shell script to print the file names of all files having .txt extension of a given directory after converting to uppercase letters. The input (directory name) should be given as command line argument. The script will also check whether sufficient arguments are passed or not and whether... (1 Reply)
A shell script is a script written for the shell, or command line interpreter, of an operating system. Typical operations performed by shell scripts include file manipulation, program execution, printing text etc.
Shell : In computing, a shell is a piece of software that provides an interface for... (1 Reply)
plz i need code to search about numbers like this :
962785785698
962795565488
962785321565
962777321684
962795979515
i need code to detect just numbers start with "96278"
i need it in awk !!
thanks (1 Reply)
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2. Relevant commands, code, scripts, algorithms:
Write a command to display lines ending with the... (1 Reply)
Discussion started by: elh009
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LEARN ABOUT OPENDARWIN
gzexe
GZEXE(1) General Commands Manual GZEXE(1)NAME
gzexe - compress executable files in place
SYNOPSIS
gzexe [ name ... ]
DESCRIPTION
The gzexe utility allows you to compress executables in place and have them automatically uncompress and execute when you run them (at a
penalty in performance). For example if you execute ``gzexe /bin/cat'' it will create the following two files:
-r-xr-xr-x 1 root bin 9644 Feb 11 11:16 /bin/cat
-r-xr-xr-x 1 bin bin 24576 Nov 23 13:21 /bin/cat~
/bin/cat~ is the original file and /bin/cat is the self-uncompressing executable file. You can remove /bin/cat~ once you are sure that
/bin/cat works properly.
This utility is most useful on systems with very small disks.
OPTIONS -d Decompress the given executables instead of compressing them.
SEE ALSO gzip(1), znew(1), zmore(1), zcmp(1), zforce(1)CAVEATS
The compressed executable is a shell script. This may create some security holes. In particular, the compressed executable relies on the
PATH environment variable to find gzip and some other utilities (tail, chmod, ln, sleep).
BUGS
gzexe attempts to retain the original file attributes on the compressed executable, but you may have to fix them manually in some cases,
using chmod or chown.
GZEXE(1)