This is the basic question.
I have read many books which advised to avoid creating sub shells.
e.g: use
rather than using
.
So, how to identify whether a command creates subshell or not?
so,is it better to use
in stead of using cat.
Whether tail or head creates sub shells?
Thanks
Hi all,
I have a shell script which calls other shell scripts, depending on the input.
Within a.sh, I have a command which calls b.sh (ie. ksh b.sh)
Normally, we use the exit function to terminate a shell. However, if I choose to call exit from b.sh, I will return to the parent shell who... (4 Replies)
hi,
i have to type certain commands again and again eg:
ps -ef | grep xyz
is there any way to replace the whole command by a short form
like i just do :
$ psl
and it give me the same output as
$ps -ef | grep xyz
where can we store these commands .....
on unix system and create... (2 Replies)
I have the following script running with nohup on one of my servers:
#!/bin/bash
#\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
#set log number
#i=1
#\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
#Check if log exits, if so incrememnt log number up so we don't clobber
#while... (8 Replies)
I've written a program in C, called count_0.1 which is essentially a word count program.
I want to be able to use it as a command in the terminal (by typing in count), like when you type in ls, you don't have to go to a directory, find an executable and type in: ./ls
I've tried:
Adding... (1 Reply)
Use and complete the template provided. The entire template must be completed. If you don't, your post may be deleted!
1. The problem statement, all variables and given/known data:
Here is what I am supposed to do, word for word from my assignment page:
1. Create/modify and print a... (2 Replies)
Hello,
I have a database of name variants with the following structure:
variant=variant=variant
The number of variants can be as many as thirty to forty.
Since the database is quite large (at present around 60,000 lines) duplicate sets of variants creep in. Thus
John=Johann=Jon
and... (2 Replies)
Can someone post a "for dummies" explanation on how subshells work?
Let's say I want to get a couple of pieces of info from the /etc/passwd file and set them as variables to be echo'd back after all data is gathered. something like
for i in ${grep 5000 /etc/passwd | cut -d : -f 5}... (5 Replies)
Hi,
I am trying to make a Shell Script using which I will update around 10K records in MySQL db each night. For that, I am currently doing the following command in FOR LOOP:
mysql -D $MASTER_DB_NAME -h $MASTER_DB_HOST -u $MASTER_DB_USER -p$MASTER_DB_PASSWD -e "$SQL_Query"
This command is... (2 Replies)
Hi there,
Everyone knows that errexit is NOT inherited by subshells. But does anyone know why errexit still appears as set with set +o?
The following example highlights the fact that errexit appears set in a subshell (set +o) even though it's actually unset (it does NOT exit with false).
$... (0 Replies)
So i have a script that is like this:
#!/bin/sh
VARA="elementary 1
elementary 2
nursery A
nursery B
highschool AZ"
echo "${ContentOfADifferentSCRIPT}" | sh
i do not have control over the script that is inside the variable "${ContentOfADifferentSCRIPT}".
however, i know that the... (3 Replies)
Discussion started by: SkySmart
3 Replies
LEARN ABOUT V7
ppmtosixel
ppmtosixel(1) General Commands Manual ppmtosixel(1)NAME
ppmtosixel - convert a portable pixmap into DEC sixel format
SYNOPSIS
ppmtosixel [-raw] [-margin] [ppmfile]
DESCRIPTION
Reads a portable pixmap as input. Produces sixel commands (SIX) as output. The output is formatted for color printing, e.g. for a DEC
LJ250 color inkjet printer.
If RGB values from the PPM file do not have maxval=100, the RGB values are rescaled. A printer control header and a color assignment table
begin the SIX file. Image data is written in a compressed format by default. A printer control footer ends the image file.
OPTIONS -raw If specified, each pixel will be explicitly described in the image file. If -raw is not specified, output will default to com-
pressed format in which identical adjacent pixels are replaced by "repeat pixel" commands. A raw file is often an order of magni-
tude larger than a compressed file and prints much slower.
-margin
If -margin is not specified, the image will be start at the left margin (of the window, paper, or whatever). If -margin is speci-
fied, a 1.5 inch left margin will offset the image.
PRINTING
Generally, sixel files must reach the printer unfiltered. Use the lpr -x option or cat filename > /dev/tty0?.
BUGS
Upon rescaling, truncation of the least significant bits of RGB values may result in poor color conversion. If the original PPM maxval was
greater than 100, rescaling also reduces the image depth. While the actual RGB values from the ppm file are more or less retained, the
color palette of the LJ250 may not match the colors on your screen. This seems to be a printer limitation.
SEE ALSO ppm(5)AUTHOR
Copyright (C) 1991 by Rick Vinci.
26 April 1991 ppmtosixel(1)