Questions tagged [shell-script]

Questions about shell scripts, executable files that are interpreted by a shell (bash, zsh, etc.).

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11
votes
2answers
2k views

date - years prior to 1901 are treated as invalid

I have date (GNU coreutils) 7.1 installed on my system. If I try to check dates prior to 14-Dec-1901, I get an "invalid date" error. For example, $ date -d 1901-12-13 date: invalid date `1901-12-...
3
votes
3answers
3k views

How to build a long command string?

I've a sequence of commands to be used along with lot of pipings, something like this: awk '{ if ($8 ~ "isad") {print $2, $5, "SE"} else {print $2, $5, "ANT"} }' "/var/log/apache2/other_vhosts_access....
0
votes
2answers
5k views

How to run a shell script containing an awk command [closed]

How to run this script (called count.sh)? awk 'BEGIN{ x=0 ; while (x < 5) { x+=1 ; print x ; } }' I'm trying to run it with sh count.sh but it's giving me an error.
8
votes
1answer
3k views

Bash script IDE

Is there a bash/ksh/any shell script IDE. Don't you get annoyed when you forget the space inside if or I don't know, some minor syntax mistakes you do from time to time, but takes you a long time to ...
2
votes
1answer
2k views

Attempting to update Amazon Route53 using a script, but domain is not being updated

I have several Amazon EC2 instances, running Ubuntu 10.04, with which I'd like to use Amazon's Route53. I setup a script as described in Shlomo Swidler's article, but I'm still missing something. ...
7
votes
3answers
9k views

How to get elapsed time from two "text based" dates

I would like to know if there is a way to calculate the difference between two times in bash. I have two fields that are extracted from a log file: Start time: Feb 12 10:02:10 End time: Feb 12 ...
8
votes
4answers
14k views

Copy/rename multiple files using regular expression (shell script)

I have a collection of files matching a pattern such as 'assignment02.cc', 'assignment02.h', 'assignment02.txt', etc. I would like to copy/rename these files into 'assignment03.cc', 'assignment03.h', '...
3
votes
4answers
994 views

shell scripts that respond to console output

Disclaimer:: I am not an active shell scripter How does one create a script that responds to console output? For instance, I'm trying to setup a cron that periodically svnsync 's changes to my ...
1
vote
2answers
1k views

How to move files with specific extensions to newly created directories

I want to mv files with specific extensions to newly created directories. This script moves files with all the extentions in all the newly created folders, which is not the intent. Instead, it should ...
19
votes
4answers
40k views

Processing bash variable with sed

bash variable LATLNG contains a latitude & longitude value in brackets like so (53.3096,-6.28396) I want to parse these into a variable called LAT and LON which I'm trying to do via sed like ...
7
votes
5answers
5k views

How to run part of a script with reduced privileges?

I have the following problem: On every machine running Postgresql there is a special user postgres. This user has administrative access to the database server. Now I want to write a Bash script that ...
3
votes
1answer
1k views

Storing `find` parameters in a variable

I'm running the following bash command: find . \( -iname '*.aif' -o -iname '*.pdf' -o -iname '*.exe' -o -iname '*.mov' \ -o -iname '*.doc' \) -exec rm -f {} \; I'm running the same parameters in ...
236
votes
20answers
292k views

How can I get distribution name and version number in a simple shell script?

I'm working on a simple bash script that should be able to run on Ubuntu and CentOS distributions (support for Debian and Fedora/RHEL would be a plus) and I need to know the name and version of the ...
3
votes
2answers
3k views

automatically load shell scripts from /usr/bin

Is there a way to have bash automatically load shell scripts I create and place into /usr/bin? Or is there a different place I should put custom shell scripts so that they are automatically loaded? ...
3
votes
1answer
15k views

Filtering on dates with grep and awk

I have created the alias below in my .bash_aliases file alias auth="grep \"$(date|awk '{print $2,$3}')\" /var/log/auth.log | grep -E '(BREAK-IN|Invalid user|Failed|refused|su|Illegal)'" ...
3
votes
2answers
5k views

Add a one-off scheduled task through a shell script?

I'd like to execute a task at a given time, once. I know I can just use crontab -e to add it there, but I'd like to do that through a shellscript. crontab -e gives me some temporary file to edit ...
3
votes
4answers
6k views

Shell script error message

I am trying to learn shell scripting by reading linuxcommand.org. For some reason I keep getting the error "Not Found", even though it runs all the commands. The error codes I get are: ...
21
votes
3answers
103k views

How can I concatenate a shell variable to other other parameters in my command lines ?

How can I concatenate a shell variable to other other parameters in my command lines? For example, #!/bin/sh WEBSITE="danydiop" /usr/bin/mysqldump --opt -u root --ppassword $WEBSITE > $WEBSITE....
4
votes
3answers
443 views

Best way to work through / display a tree of images sorted by size

I've got a deep directory tree containing .PNG files. I'd like to find all the .PNG files in the directory, sort them in order of size from smallest to largest, and then display every 50th image. (I'...
11
votes
1answer
4k views

How do I make a shell script that sends output to a process

I'm currently running a server console program in a screen because I need to both read it and occasionally send commands. I'd like to run the app as a daemon in the background (start/stop it with ...
21
votes
2answers
11k views

How do I test to see if an application exists in $PATH?

I'm trying to write all of my sh startup/env scripts to work with as much DRY and as much: "works on every *nix I clone it to", as possible. This means making sure that if I try to run code that's not ...
2
votes
1answer
294 views

Why does the local::lib shell code use eval and $()

using local::lib requires you to add a line to your ~/.shellrc eval $(perl -I$HOME/perl5/lib/perl5 -Mlocal::lib) I don't understand what the point of using eval, and encasing the statement in $() is....
24
votes
4answers
5k views

keep duplicates out of $PATH on source [duplicate]

I have the following code that's source-d by my .shellrc PATH="${PATH}:${HOME}/perl5/bin" PATH="${PATH}:${HOME}/.bin" export PATH but if I make changes to other code and then source this file, my ...
187
votes
5answers
81k views

$VAR vs ${VAR} and to quote or not to quote

I can write VAR=$VAR1 VAR=${VAR1} VAR="$VAR1" VAR="${VAR1}" the end result to me all seems about the same. Why should I write one or the other? are any of these not portable/POSIX?
11
votes
4answers
15k views

Bash script to detect the version control system by testing command return status

I am working on a bash script that I would like to work for several types of VCS. I am thinking of testing if a directory is a repo for a system by running a typical info command and checking the ...
30
votes
4answers
137k views

Storing output of command in shell variable [duplicate]

I have an operation using cut that I would like to assign result to a variable var4=echo ztemp.xml |cut -f1 -d '.' I get the error: ztemp.xml is not a command The value of var4 never gets ...
8
votes
1answer
5k views

Recursively compare directory contents by name, ignoring file extensions

I have a directory containing about 7,000 music files. I used lame to recursively re-encode all files in it to a separate directory, outputting all files with the same relative path and file name. ...
8
votes
1answer
4k views

Reason for ksh obsoleting -eq

The latest version of ksh obsoletes using -eq within [[ ]] blocks, prefering (( )) instead. Why is this? I can't find any documentation on the advantages of (( )) over [[ ]] anywhere, and I find that ...
42
votes
4answers
10k views

aliasing cd to pushd - is it a good idea?

Is it a good idea to use the following alias: cd() { pushd $1; } in bash? I think this would be very useful, since I can then use a series of popds instead of just a cd - once. Is there any ...
6
votes
4answers
5k views

Why do I need to hit enter to get my shell prompt after my init.d script completes?

I had to write my own CentOS init.d script for celery because it only ships with one for Debian. You can see the script I wrote when I answered my own stack overflow question 3989656. But there's a ...
5
votes
2answers
709 views

Simple "Variable" Bash File

I just want to make a bash file that takes a file name as a parameter. In that bash file, I want to take the name before the extension and have it as a "variable", to use in other places. For example, ...
31
votes
1answer
75k views

In Bash, are if [ -z "$1" ] and if [ "$1" = "" ] the same?

In Bash shell scripting, what is the difference (if any) between the following two statements? if [ -z "$1" ] if [ "$1" = "" ] I have found myself writing the second ...
4
votes
2answers
4k views

How to write a script to execute files in multiple directories

How do I write a script to execute the files in multiple directories? The problem is this: I have many directories, and each has a data file to be read and analyzed by a python script (say, a.py). I ...
12
votes
2answers
96k views

./executable: cannot execute binary file

I have a script that works well when I ssh to the server to execute it myself, but has problems when Hudson, a continuous integration server, runs it. I am automating tests on an embedded linux ...
7
votes
2answers
1k views

Strip // Comments From Files

What's the best way to strip all code comments in a given directory? I'd like to strip out all // ... EOL comments, and /* blah \*/ (or /** ... \*/) comments as well. This is a PHP project, and I'd ...
16
votes
4answers
35k views

Remove end of line characters from stdout? Multiple lines into a single line

I have a script which outputs the following text. This is the output from a Netopia 2210-02 ADSL2 modem. ADSL Line State: Up ADSL Startup Attempts: 1 ADSL Modulation: DMT ADSL Data ...
5
votes
3answers
3k views

renaming files without the **rename** command

I have a directory of files, Measurements Panama 2009-03-22 Session1.xml Measurements Panama 2009-03-22 Session2.xml Measurements Panama 2009-03-22 Session3.xml Measurements Panama 2009-03-22 ...
45
votes
8answers
75k views

Different ways to execute a shell script

There are several ways to execute a script. The ones I know are: /path/to/script # using the path (absolute or relative) . script # using the . (dot) source script # using the `source` ...

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