06-11-2010
Unless you have GNU date there is no simple code to do this. CFA Johnson, a forum member, has a website with a shell script library to do date arithmetic. The code is good, but doing dates in shell in an involved.
Rolling your own date routines is not best practice. Finding yesterday when the date today is March 1 is a classic example. You have to know whether it is a leap year or not, then roll back to Feb 28 or 29.
The standard way to get yesterday:
calculate the current Julian day, subtract one, then convert Julian -> Gregorian date.
get current time in UNIX epoch seconds and subtract 86400, then convert epoch seconds to a Gregorian date.
For production systems always use known good libraries for date calculations.
10 More Discussions You Might Find Interesting
1. Shell Programming and Scripting
Hi,
I am writing a script which takes the input file name and concat as a new file by appending a "1" to the file name. However i am not able to get the size of this new file. I am not sure where i am going wrong. Please check the script and help me get this working.
#!/bin/sh ... (1 Reply)
Discussion started by: ragsnovel
1 Replies
2. Shell Programming and Scripting
i tried to use "find" to get all of yesterdays files but missed something in the 24 hours logic.
can anybody help me with this one?
i thought that -daystart -atime 1 was enough but i got more files (2 Replies)
Discussion started by: progressdll
2 Replies
3. Shell Programming and Scripting
I need to get yesterdays date in the format yyyymmdd
I can get today's date simply enough - 20031112
Is there any way to substract 1 from this easily enough in korn shell script?
It has to be korn shell and not perl (20 Replies)
Discussion started by: frustrated1
20 Replies
4. UNIX for Dummies Questions & Answers
hiiii
shell script to find noof characters in a file name, when you run ls -l (using awk)
I tried with this
ls -l > temp
awk -F"," '{print $1 " " expr length $9}' temp
but it give some other value instead of file name length (error value like , 563,54,55,56....).How to prnint the... (10 Replies)
Discussion started by: krishnampkkm
10 Replies
5. Shell Programming and Scripting
I need help as to how to write a script in Unix for the following:
We have 3 servers;
The mainframe will FTP them to a folder. In that folder we will need the script to look and see if the specific file name is there and load it to the correct table.
Can anyone pls help me out with... (2 Replies)
Discussion started by: msrahman
2 Replies
6. Shell Programming and Scripting
Right, noob to shell scripting, playing a round for practice, wrote the following but it doesn't seem to work as expected, how could I fix/improve this script?
#!/bin/bash
#set -v
#set -x
case $# in
1)
echo Searching for $1 in '*';
find . -iname '*' 2>/dev/null | xargs grep "$1" -sl... (3 Replies)
Discussion started by: Pezmc
3 Replies
7. UNIX for Dummies Questions & Answers
Hi,
I am new to shell scripting. I need a bash shell scripts which search and grep a parameter value from input.txt file and insert it in between two semicolon of second line of output.txt file.
For example
The shell script search an IP address as parameter value from input.txt ... (2 Replies)
Discussion started by: sunilkumarsinha
2 Replies
8. Shell Programming and Scripting
How to find and remove invalid URLs in a text file using shell script? (1 Reply)
Discussion started by: vel4ever
1 Replies
9. UNIX for Dummies Questions & Answers
echo "******Select Option:******"
echo "1 - script1"
echo "2 - script2"
echo "3 - script3 "
read option
echo "You have selected" $option"."
if
then /scratch/username/script1.sh
elif
then /scratch/username/script2.sh
elif
then /scratch/username/script3.sh
else
echo "Please try again... (12 Replies)
Discussion started by: Dish
12 Replies
10. Homework & Coursework Questions
1. The problem statement, all variables and given/known data:
Write a shell script that takes a single command line parameter, a file path (might be relative or absolute). The script should examine that file and print a single line consisting of the phrase:
Windows ASCII
if the files is an... (4 Replies)
Discussion started by: kwatt019
4 Replies
LEARN ABOUT FREEBSD
atf-sh
ATF-SH(1) BSD General Commands Manual ATF-SH(1)
NAME
atf-sh [-s shell] -- interpreter for shell-based test programs
SYNOPSIS
atf-sh script
DESCRIPTION
atf-sh is an interpreter that runs the test program given in script after loading the atf-sh(3) library.
atf-sh is not a real interpreter though: it is just a wrapper around the system-wide shell defined by ATF_SHELL. atf-sh executes the inter-
preter, loads the atf-sh(3) library and then runs the script. You must consider atf-sh to be a POSIX shell by default and thus should not
use any non-standard extensions.
The following options are available:
-s shell Specifies the shell to use instead of the value provided by ATF_SHELL.
ENVIRONMENT
ATF_LIBEXECDIR Overrides the builtin directory where atf-sh is located. Should not be overridden other than for testing purposes.
ATF_PKGDATADIR Overrides the builtin directory where libatf-sh.subr is located. Should not be overridden other than for testing purposes.
ATF_SHELL Path to the system shell to be used in the generated scripts. Scripts must not rely on this variable being set to select a
specific interpreter.
EXAMPLES
Scripts using atf-sh(3) should start with:
#! /usr/bin/env atf-sh
Alternatively, if you want to explicitly choose a shell interpreter, you cannot rely on env(1) to find atf-sh. Instead, you have to hardcode
the path to atf-sh in the script and then use the -s option afterwards as a single parameter:
#! /path/to/bin/atf-sh -s/bin/bash
ENVIRONMENT
ATF_SHELL Path to the system shell to be used in the generated scripts.
SEE ALSO
atf-sh(3)
BSD
September 27, 2014 BSD