The for loop should end with a simple done.
Indeed a for loop is made to cycle through a list in memory; if the list is made from a file then the whole file must fit into memory.
In contrast, a while-read loop reads a file line by line. Most efficient if you can read each field into a distinct variable.
Quoting a lone $var in an assignment is not needed.
But quoting is a must in command arguments
Last edited by MadeInGermany; 12-04-2016 at 07:17 AM..
This User Gave Thanks to MadeInGermany For This Post:
I have a command nested in some while loops to parse some data that looks something like this.
while ($condition)
while ($condition)
...
gzcat /dir/$fileName.gz | grep $searchString > out_file
end
end
On the first loop, the command is executed properly (and takes maybe 10... (3 Replies)
i have a line like this in my script
IP=`get_IP <hostname> | awk '{ print $1 }'
echo $IP
the problem is get_IP <hostname> returns data formated as follows:
ip 1.1.1.1 name server_name
the code above returns
1.1.1.1 server_name and i just need the 1.1.1.1
I have tried to add "|... (5 Replies)
Hi I am using a awk command but not getting required o/p.
input file
a.txt
2 ak
3 cb
4 de
5 gh
6 ij
awk program
BEGIN { x=0 }
{if ($1>3) {x=x+1}{print $0} }
END { print "I found " x " line have value more than 3" }
output
2 ak
3 cb
4 de
5 gh
6 ij (3 Replies)
Hello,
Recently, I've started with shell scripting, and decided to write a script for my system backup using tar. When I was dealing with tar execution inside shell script I found this, inside shell we have the following code:
tar $TAR_PARAMS $ARCHIVE_FILE $EXCLUDE $BACKUP_STARTwith... (6 Replies)
Hey everyone
I have a file 'agenda' which contains:
Object Day Month Year
Birthday 09 02 2012
i want to extract from a script the line which contains the day the user typed.
for example if he type 09 the line is showed using... (4 Replies)
#!/bin/bash
#...
for i in `ls -c1 /usr/share/applications`
do
name="cat $i | grep ^Name= | cut -d = -f2"
echo $name
#...
done
Now inside name as output is present:
while i want only the result of the command.
Ideally i would like obtain that information using only bash ... or... (8 Replies)
Hello,
There is a process in AIX which is actually a oracle database user session but is running very slow When I use lsof it give below output
lsof /proc/21955180
In while loop:256
In while loop:256
In while loop:256
In while loop:256
Value of I :183 np:1024
Please... (1 Reply)
#!/bin/sh
# This script returns the number of rows updated from a function
echo "The execution is starting ....."
sqlplus -silent $UP <<EOF
set serveroutput on
set echo off
set pagesize 0
VAR no_rows_updated NUMBER;
EXEC :no_rows_updated :=0;
DECLARE
CURSOR c_update is
SELECT * FROM... (4 Replies)
Hello,
I am running below command as root user
#nodetool cfstats tests | grep "Memtable switch count"
Memtable switch count: 12
Where as when I try to run same command as another user it gives different result.
#su -l zabbix -s /bin/bash -c "nodetool cfstats tests | grep "Memtable switch... (10 Replies)
Discussion started by: Pushpraj
10 Replies
LEARN ABOUT MOJAVE
cut
CUT(1) BSD General Commands Manual CUT(1)NAME
cut -- cut out selected portions of each line of a file
SYNOPSIS
cut -b list [-n] [file ...]
cut -c list [file ...]
cut -f list [-d delim] [-s] [file ...]
DESCRIPTION
The cut utility cuts out selected portions of each line (as specified by list) from each file and writes them to the standard output. If no
file arguments are specified, or a file argument is a single dash ('-'), cut reads from the standard input. The items specified by list can
be in terms of column position or in terms of fields delimited by a special character. Column numbering starts from 1.
The list option argument is a comma or whitespace separated set of numbers and/or number ranges. Number ranges consist of a number, a dash
('-'), and a second number and select the fields or columns from the first number to the second, inclusive. Numbers or number ranges may be
preceded by a dash, which selects all fields or columns from 1 to the last number. Numbers or number ranges may be followed by a dash, which
selects all fields or columns from the last number to the end of the line. Numbers and number ranges may be repeated, overlapping, and in
any order. If a field or column is specified multiple times, it will appear only once in the output. It is not an error to select fields or
columns not present in the input line.
The options are as follows:
-b list
The list specifies byte positions.
-c list
The list specifies character positions.
-d delim
Use delim as the field delimiter character instead of the tab character.
-f list
The list specifies fields, separated in the input by the field delimiter character (see the -d option.) Output fields are separated
by a single occurrence of the field delimiter character.
-n Do not split multi-byte characters. Characters will only be output if at least one byte is selected, and, after a prefix of zero or
more unselected bytes, the rest of the bytes that form the character are selected.
-s Suppress lines with no field delimiter characters. Unless specified, lines with no delimiters are passed through unmodified.
ENVIRONMENT
The LANG, LC_ALL and LC_CTYPE environment variables affect the execution of cut as described in environ(7).
EXIT STATUS
The cut utility exits 0 on success, and >0 if an error occurs.
EXAMPLES
Extract users' login names and shells from the system passwd(5) file as ``name:shell'' pairs:
cut -d : -f 1,7 /etc/passwd
Show the names and login times of the currently logged in users:
who | cut -c 1-16,26-38
SEE ALSO colrm(1), paste(1)STANDARDS
The cut utility conforms to IEEE Std 1003.2-1992 (``POSIX.2'').
HISTORY
A cut command appeared in AT&T System III UNIX.
BSD December 21, 2006 BSD