Home > Not Working > Bash If Statement Not Working

Bash If Statement Not Working

Contents

This makes our boolean idiom a bit more convenient: var=1 # POSIX if [ "$var" -eq 1 ]; then # ... fi # bash, zsh, etc if ((var)); then # ... fi # example use-case. $UID of the elif (else if) ladder are useful where we have multiple programs for execution and need to execute only one based on results of if and elif condition. How can Average Joe create a micro-state that is a member of the UN in the least amount of time? When the SGID-bit is set on a directory, all files created in that directory will inherit the group of the directory.

if [ -g . ]; then echo "Created files Check This Out

Join them; it only takes a minute: Sign up Bash if statement not working properly up vote 2 down vote favorite I have a bash statement to test a command line Then I tried Mark's suggestion: Code: FILE_EXT=${FILE%log.bz2} and that returned an empty string... Hide/Suppress equations by only changing preamble? Different condition syntaxes Bash features different syntaxes for conditions. http://stackoverflow.com/questions/22892878/conditions-in-shell-script-not-working

Bash If Statement Not Working

Syntax The general syntax of an if statement in any POSIX shell is as follows: if command ; then expressions elif command ; then # optionally expressions else # optionally expressions fi The if This will be faster since it’s only one program invocation: if test "$foo" != 'bar' -a "$foo" != 'baz'; then # $foo is not bar or baz fi The [ Command Surprisingly, Note that the and operator has precedence over the or operator, meaning that "&&" or "-a" will be evaluated before "||" or "-o".

Draw diagonal lines of text Build me a brick wall! Are there 2-3m illegal migrants with criminal records in the USA? They produce all kinds of problems which were solved with the [[...]] syntax. If Else Bash Search for: CategoriesCategories Select Category Amazon Web Services Announcements Apple Azure Behind the Scenes Big Data Cloud Cloud Cadet DevOps Finance Game Dev Geek jQuery Mobile Linux linuxacademy.com Mobile Month of

Which security measures make sense for a static web site? Bash != Not Working Some random examples:

if [ $? -eq 0 ]; then # $? Thus [ $ARG=="clean" ] will always return true. http://stackoverflow.com/questions/21530844/unix-bash-if-else-statement-not-working Products Pentaho BI Suite - Pentaho Reporting - Pentaho Analysis - Pentaho Dashboards - Pentaho Data Integration (ETL) - Pentaho Data Mining On-Demand BI Subscription Demos / Recordings, White Papers Test

What is the difference between two condition evaluation approaches in bash Can spacecraft defend against antimatter weapons? Bash Check If File Exists When dealing with globs and regular expressions, we immediately come to another rule: Rule: Never quote a glob or regular expression I know, I just said to quote everything, but the Bash if Statement Single if statements are useful where we have a single program for execution. Conclusion To recap, we’ve seen that if in the Unix shell is both simple and complex.

Bash != Not Working

See pages that link to and include this page. http://www.unix.com/shell-programming-and-scripting/46570-if-statement-not-working.html Double-bracket syntax You may have encountered conditions enclosed in double square brackets already, which look like this: if [[ "$stringvar" == *string* ]]; then The double-bracket syntax serves as an enhanced Bash If Statement Not Working This can lead to some nonsensical statements. Bash String Not Equal Message from terminal $(tty) to you." > /dev/pts/3 # Anyone using that terminal will actually see this message!

Remove advertisements Sponsored Links Hazmeister View Public Profile Find all posts by Hazmeister #6 12-13-2007 prowla Read Only Join Date: Nov 2007 Last Activity: 16 July 2012, 4:02 his comment is here Since commands can be chained together logically with && and ||, we can combine conditions intuitively: if test "$foo" != 'bar' && test "$foo" != 'baz'; then # $foo is not Example: if [ ! -f regularfile ]; then Be sure to place the "!" inside the brackets! To add an else, we just use standard syntax. #!/bin/bash if [ "$1" = "cool" ] then echo "Cool Beans" else echo "Not Cool Beans" fi Adding an else-if statement structure Bash If Condition

if [ -a tmp.tmp ]; then rm -f tmp.tmp # Make sure we're not bothered by an old temporary file fi [ -b blockspecialfile ] file ‘blockspecialfile' exists and is But for some strange reason this fails in Kettle, but works fine from the command line. if [ /mnt/remote/remotefile -ot localfile ]; then cp -f localfile /mnt/remote/remotefile # Make sure the remote location has the newest version of the file, too fi [ same -ef file http://virtualthought.net/not-working/javascript-not-working-in-firefox-but-working-in-chrome.html Rule: Never use [[ for numeric comparisons.

Password Home Search Forums Register Forum RulesMan PagesUnix Commands Linux Commands FAQ Members Today's Posts Shell Programming and Scripting BSD, Linux, and UNIX shell scripting Post awk, bash, csh, ksh, For that, we’ll use (( which I’ll explain shortly. If you haven't done that, do so and try it again.

It may sound strange, but surrounding a comparison with square brackets is the same as using the built-in test command, like this: if test $foo -ge 3; then If $foo is

Arithmetic (number-based) conditions: Condition True if Example/explanation [ NUM1 -eq NUM2 ] NUM1 is EQual to NUM2. So I resorted to good old sed: Code: FILE_EXT=$(echo "$FILE" | sed 's/^.*\.//') and this works fine and returns "bz2". Browse other questions tagged linux shell unix or ask your own question. fi

Note: you can also use a single "=" instead of a double one. [ STRING1 != STRING2 ] STRING1 is not equal to STRING2.

Locations Austin, TX Boston, MA London, UK New York, NY Raleigh, NC San Francisco, CA Washington, DC Podcasts The Bike Shed Build Phase Giant Robots Tentative © 2016 thoughtbot, inc. What are the benefits of referential transparency to a programmer? For more string-based conditions see the table below. navigate here In cases where it’s not, some shells offer the pipefail option to change that behavior.

if [ story.txt1 -nt story.txt ]; then echo "story.txt1 is newer than story.txt; I suggest continuing with the former." fi [ olderfile -ot newerfile ] file ‘olderfile' was changed longer The idiomatic (and more efficient) way to represent booleans in shell scripts is with the values 1 (for true) and 0 (for false). Should I have doubts if the organizers of a workshop ask me to sign a behavior agreement upfront? Miscellaneous conditions: Condition True if Example/explanation [ -o shelloption ] shell option ‘shelloption' is enabled.

How do I deal with my current employer not respecting my decision to leave? View/set parent page (used for creating breadcrumbs and structured layout). And so I will. share|improve this answer edited Feb 3 '14 at 15:31 answered Feb 3 '14 at 15:17 Aaron Digulla 205k60368577 Though i change it., It says missing ` ; -bash-3.00$ if

if [ condition ] then fi For example - If we need to check if input value is equal to 10 or not. As a succesful execution doesn't require any explanation, it needs only one exit status. Popular Posts Which OS Should You Run on Your NAS How to Set Up a Profitable eCommerce Business © Copyright 2013-2016 TecAdmin.net. This program will work with numeric values only.

If you'd like to match both "String" and "string", you could use the following syntax: if [[ "$stringvar" == *[sS]tring* ]]; then Note that only general shell globbing is allowed. See man 1 test for all available numeric comparisons. I will illustrate this difference using two examples, starting with the old single-bracket situation: if [ -a *.sh ]; then The above condition will return true if there is one single Wrong password!" exit 1 # Stops script execution right here fi [ STRING1 > STRING2 ] STRING1 sorts after STRING2 in the current locale (lexographically).

The reason behind this is that shells like bash deal with programs a lot. It does nothing but execute a command and branch based on exit status. else rm "archive/$FILE"; fi done Reply With Quote 06-28-2011,06:25 AM #6 MattCasters View Profile View Forum Posts Visit Homepage Chief Data Integration Join Date Nov 1999 Posts 9,727 put set -x Yes, conditions are commands.