Sponsored Content
Full Discussion: head usage
Top Forums Shell Programming and Scripting head usage Post 302168260 by qneill on Sunday 17th of February 2008 09:50:04 PM
Old 02-17-2008
Quote:
Originally Posted by vasuarjula
$ct=1
head -n $ct file.
A good debugging technique in most shells is to use "-x" which prints each command as it is executed. I put your commands in a script named 'yourscript'
Code:
bash$ cat yourscript                          # see the script
$ct=1
head -n $ct file

and then execute with -x:
Code:
bash$ bash -x yourscript                  # execute the script with -x
+ =1                                      # notice '$ct' is blank (you want 'ct')
script: line 1: =1: command not found     # which causes problems
+ head -n file                            # '$ct' is again blank
head: file: invalid number of lines       # more problems

Here's your corrected script (using 'ct=1')
Code:
bash$ cat yourscript 
ct=1
head -n $ct file
bash$ cat file
blah blah one
blah blah two
bash$ bash -x yourscript 
+ ct=1
+ head -n 1 file
blah blah one

 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

help.. I am in way over my head !!!!

my boss has done it again I have been sent to fix a unix issue and I ma hoping you can help three issues 1st. I have a printer that when you try to print to it the print job comes out on a diffrent printer. If I take the printer ( dot matrix thourgh a serail connection) to a diffrent local the... (3 Replies)
Discussion started by: oberon42
3 Replies

2. Programming

Monitor CPU usage and Memory Usage

how can i monitor usages of CPU, Memory, Hard disk etc. under SUN Solaries through a c program or java program i want to store that data into database so i can show it graphically thanks in advance (2 Replies)
Discussion started by: Gajanad Bihani
2 Replies

3. Shell Programming and Scripting

head command

Hi All, How can the head command be used to extract only a particular line. By default head -n filename displays the first n lines. I want only the nth line. I couldn't get it from forum search. Thanks, Sumesh (6 Replies)
Discussion started by: sumesh.abraham
6 Replies

4. HP-UX

how can I find cpu usage memory usage swap usage and logical volume usage

how can I find cpu usage memory usage swap usage and I want to know CPU usage above X% and contiue Y times and memory usage above X % and contiue Y times my final destination is monitor process logical volume usage above X % and number of Logical voluage above can I not to... (3 Replies)
Discussion started by: alert0919
3 Replies

5. Solaris

current CPU usage, memory usage, disk I/O oid(snmp)

Hi, I want to monitor the current cpu usage, monitor usage , disk I/o and network utlization for solaris using SNMP. I want the oids for above tasks. can you please tell me that Thank you (2 Replies)
Discussion started by: S_venkatesh
2 Replies

6. Shell Programming and Scripting

head followed by variable??

I know that the common use of head is for example head -3 etc.Is there any possibility that,if i have a variable that equals to an integer(i=5),i can write head -i?? If not,what syntax or commands should i write down in order to have the same result? //maybe something lik head -"$variable" ? (2 Replies)
Discussion started by: bashuser2
2 Replies

7. AIX

How to monitor the IBM AIX server for I/O usage,memory usage,CPU usage,network..?

How to monitor the IBM AIX server for I/O usage, memory usage, CPU usage, network usage, storage usage? (3 Replies)
Discussion started by: laknar
3 Replies

8. UNIX for Dummies Questions & Answers

find and head -1

i have lots of files in /law/prod and /law/dev, such as AP20PD, AP20WS, AP20.scr, AP20.rpt if i am in /law DIR find . -name AP20PD, found in /law/prod and /law/dev i want to head -1 AP20PD from both location and >> /tmp/test.log can i use find and head in one line ? ----------... (1 Reply)
Discussion started by: tjmannonline
1 Replies

9. UNIX for Dummies Questions & Answers

Command to display the space usage (memory usage) of a specific directory.

Hi all, Can you please tell me the command, with which one can know the amount of space a specific directory has used. df -k . ---> Displays, the amount of space allocated, and used for a directory. du -k <dir name> - gives me the memory used of all the files inside <dir> But i... (2 Replies)
Discussion started by: abhisheksunkari
2 Replies

10. UNIX for Dummies Questions & Answers

Memory usage per user,percent usage,sytem time in ksh

Let's say i have 20 users logged on Server. How can I know how much memory percent used each of them is using with system time in each user? (2 Replies)
Discussion started by: roy1912
2 Replies
LIBBASH(7)							  libbash Manual							LIBBASH(7)

NAME
libbash -- A bash shared libraries package. DESCRIPTION
libbash is a package that enables bash dynamic-like shared libraries. Actually its a tool for managing bash scripts whose functions you may want to load and use in scripts of your own. It contains a 'dynamic loader' for the shared libraries ( ldbash(1)), a configuration tool (ldbashconfig(8)), and some libraries. Using ldbash(1) you are able to load loadable bash libraries, such as getopts(1) and hashstash(1). A bash shared library that can be loaded using ldbash(1) must answer 4 requirments: 1. It must be installed in $LIBBASH_PREFIX/lib/bash (default is /usr/lib/bash). 2. It must contain a line that begins with '#EXPORT='. That line will contain (after the '=') a list of functions that the library exports. I.e. all the function that will be usable after loading that library will be listed in that line. 3. It must contain a line that begins with '#REQUIRE='. That line will contain (after the '=') a list of bash libraries that are required for our library. I.e. every bash library that is in use in our bash library must be listed there. 4. The library must be listed (For more information, see ldbashconfig(8)). Basic guidelines for writing library of your own: 1. Be aware, that your library will be actually sourced. So, basically, it should contain (i.e define) only functions. 2. Try to declare all variables intended for internal use as local. 3. Global variables and functions that are intended for internal use (i.e are not defined in '#EXPORT=') should begin with: __<library_name>_ For example, internal function myfoosort of hashstash library should be named as __hashstash_myfoosort This helps to avoid conflicts in global name space when using libraries that come from different vendors. 4. See html manual for full version of this guide. AUTHORS
Hai Zaar <haizaar@haizaar.com> Gil Ran <ril@ran4.net> SEE ALSO
ldbash(1), ldbashconfig(8), getopts(1), hashstash(1) colors(1) messages(1) urlcoding(1) locks(1) Linux Epoch Linux
All times are GMT -4. The time now is 06:01 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy