Sponsored Content
Top Forums Shell Programming and Scripting What does this shell script do? Need in depth explanation please Post 302982164 by shadowknight777 on Sunday 25th of September 2016 07:43:25 PM
Old 09-25-2016
What does this shell script do? Need in depth explanation please

Hi

My friend wrote this particular script and won't tell me what it does, and when I run it I don't understand it.

What does the entire script do with specifics please.

Thanks
Bob

Code:
#!/bin/bash
current=0
while [ $SECONDS -le 10 ]; do
if [ $SECONDS -eq ${current} ]; then
echo ${current}
current=$((${current}+1))
fi
done


Last edited by Don Cragun; 09-25-2016 at 11:44 PM.. Reason: Add CODE tags.
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

any explanation for thsi shell script behaviour

hello whats the difference between excuting a shell script as a)sh myscript.sh b). ./myscript.sh i noticed that my shell script works fine when i run it as . ./myscript .sh but fails when i run it as sh myscript.sh could anybody explain why. the shell script is very simple ... (9 Replies)
Discussion started by: xiamin
9 Replies

2. Shell Programming and Scripting

Script explanation

I have the following script awk '$1 ~ /^*+/ { s += $NF; m++ } END { print NR, m, s } and I use it to get results from the following file A4792 4 COMP9021 5 K9 7 ABC 8 924 1 R2D2 3 (8 Replies)
Discussion started by: sickboy
8 Replies

3. Shell Programming and Scripting

Need explanation of script

Hi All, Can anybody explain what this script is doing? #!/bin/sh who | cut -d " " -f1 | sort -u > userlist1 while true ; do sleep 60 who | cut -d" " -f1 | sort -u >userlist2 for username in `cat userlist1` ; do if ! grep "^$username$" userlist2 > /dev/null ; then echo... (0 Replies)
Discussion started by: vishalpatel03
0 Replies

4. Shell Programming and Scripting

explanation for a script

Guys, was wondering what the meaning of the below bit is ? awk -F ' ' '{print $1 " " $2 ;}' $TEMPFILE | (rm -f $TEMPFILE; sed 's/$/ '"$box"'/g' > $TEMPFILE) Can anyone explain this in detail? what is the significance of rm -f $TEMPFILE here? What all IO/buffering happens here ?How the... (0 Replies)
Discussion started by: hashin_p
0 Replies

5. Shell Programming and Scripting

Shell Script Explanation

Hello, I have seen this script on this site. I understand most of it. However I am a bit stuck on the part in red. It appears to be expanding for file in *.zip do zipdir=${file%.*} mkdir $zipdir || echo "unable to create $zipdir" cp $file $zipdir || echo "unable to copy $file"... (3 Replies)
Discussion started by: jaysunn
3 Replies

6. Shell Programming and Scripting

Script explanation

#script fileused=test.txt hostname=test.dis.com ftp $hostname <<-! > $fileused.err 2>&1 put file.txt /usr/text.txt bye ! kindly the above script the one marked as Bold and underlined as the above i am declaring the new variable as filename ,But when i used i had used as $fileused.err... (1 Reply)
Discussion started by: rajar_r
1 Replies

7. Shell Programming and Scripting

need an explanation on this script...

The following script will create a directory in a directory and will go on as many times as the number you will give in. I am trying to find out how it works ... can someone please help me with that? #!/bin/sh #create a variable and set it to 1 n=1 #start a loop as... (3 Replies)
Discussion started by: I-1
3 Replies

8. Solaris

Explanation of script

Hello Guys, can someone help explain the script below for me? I will really appreciate it. vi db_script #!/bin/sh echo .cron job run on.`date`> cronjob.txt df -h >> cronjob.txt echo welcome to home (2 Replies)
Discussion started by: cjashu
2 Replies

9. Shell Programming and Scripting

How to write Perl Script to Get MQ Queue Depth?

Hi , I got the following script from internet to display queue depth using Perl Script. However, when I execute it , im getting following error. Can anyone shed light on what is going wrong? #!/usr/bin/perl ## 07/23/01 ## Depth Inquiry sample program. ## Arguments: ## Connects to... (11 Replies)
Discussion started by: srkmish
11 Replies

10. Shell Programming and Scripting

Shell script explanation

Hey, can someone explain me this script? i=0 while read WORT do echo $WORT|grep a>/dev/null || echo$WORT|grep B>dev/null || let i=$i+1 done echo $i The first lane initializie the variable i with the value of 0. The loop line has 3 different options because of ||. The only option I... (10 Replies)
Discussion started by: newuser21
10 Replies
SCRIPT(1)                                                          User Commands                                                         SCRIPT(1)

NAME
script - make typescript of terminal session SYNOPSIS
script [options] [file] DESCRIPTION
script makes a typescript of everything displayed on your terminal. It is useful for students who need a hardcopy record of an interactive session as proof of an assignment, as the typescript file can be printed out later with lpr(1). If the argument file is given, script saves the dialogue in this file. If no filename is given, the dialogue is saved in the file type- script. OPTIONS
-a, --append Append the output to file or to typescript, retaining the prior contents. -c, --command command Run the command rather than an interactive shell. This makes it easy for a script to capture the output of a program that behaves differently when its stdout is not a tty. -e, --return Return the exit code of the child process. Uses the same format as bash termination on signal termination exit code is 128+n. -f, --flush Flush output after each write. This is nice for telecooperation: one person does `mkfifo foo; script -f foo', and another can supervise real-time what is being done using `cat foo'. --force Allow the default output destination, i.e. the typescript file, to be a hard or symbolic link. The command will follow a symbolic link. -q, --quiet Be quiet (do not write start and done messages to standard output). -t[file], --timing[=file] Output timing data to standard error, or to file when given. This data contains two fields, separated by a space. The first field indicates how much time elapsed since the previous output. The second field indicates how many characters were output this time. This information can be used to replay typescripts with realistic typing and output delays. -V, --version Display version information and exit. -h, --help Display help text and exit. NOTES
The script ends when the forked shell exits (a control-D for the Bourne shell (sh(1)), and exit, logout or control-d (if ignoreeof is not set) for the C-shell, csh(1)). Certain interactive commands, such as vi(1), create garbage in the typescript file. script works best with commands that do not manipulate the screen, the results are meant to emulate a hardcopy terminal. It is not recommended to run script in non-interactive shells. The inner shell of script is always interactive, and this could lead to unexpected results. If you use script in the shell initialization file, you have to avoid entering an infinite loop. You can use for example the .profile file, which is read by login shells only: if test -t 0 ; then script exit fi You should also avoid use of script in command pipes, as script can read more input than you would expect. ENVIRONMENT
The following environment variable is utilized by script: SHELL If the variable SHELL exists, the shell forked by script will be that shell. If SHELL is not set, the Bourne shell is assumed. (Most shells set this variable automatically). SEE ALSO
csh(1) (for the history mechanism), scriptreplay(1) HISTORY
The script command appeared in 3.0BSD. BUGS
script places everything in the log file, including linefeeds and backspaces. This is not what the naive user expects. script is primarily designed for interactive terminal sessions. When stdin is not a terminal (for example: echo foo | script), then the session can hang, because the interactive shell within the script session misses EOF and script has no clue when to close the session. See the NOTES section for more information. AVAILABILITY
The script command is part of the util-linux package and is available from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils /util-linux/>. util-linux June 2014 SCRIPT(1)
All times are GMT -4. The time now is 02:01 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy