List of 'if' switches anywhere?

list of e
list.of java
category name list
list of s
wikipedia categories list
list of p
list of lists to make
list of lists python

Is there a list of all the if switches for use in bash scripting? Sometimes I see someone using it and I wonder what the switch they're using actually does.

Example is the -z in this one. I know how to use it, but I don't know where it was derived from.

if [ -z "$BASH_VERSION" ]; then
    echo -e "Error: this script requires the BASH shell!"
    exit 1
fi

Any references, guides, posts, answers would be appreciated.

Look at the bash manpage (man bash). The options are specified in the CONDITIONAL EXPRESSIONS section:

CONDITIONAL EXPRESSIONS
       Conditional expressions are used by the [[  compound  command  and  the
       test  and [ builtin commands to test file attributes and perform string
       and arithmetic comparisons.  Expressions are formed from the  following
       unary  or  binary  primaries.   If any file argument to one of the pri-
       maries is of the form /dev/fd/n, then file descriptor n is checked.  If
       the  file  argument  to  one  of  the  primaries  is one of /dev/stdin,
       /dev/stdout, or /dev/stderr, file descriptor 0, 1, or 2,  respectively,
       is checked.

       Unless otherwise specified, primaries that operate on files follow sym-
       bolic links and operate on the target of the link, rather than the link
       itself.

       -a file
              True if file exists.
       ... more options ...

It is also explained in the help:

$ help [ [: [ arg... ]
    This is a synonym for the "test" builtin, but the last
    argument must be a literal `]', to match the opening `['.

Category:Lists of lists, If something is wrong with an entry other than simply having slightly outdated statistics, post about it on the talk page. Lists of Wikipedias by various criteria: edit​. Define list. list synonyms, list pronunciation, list translation, English dictionary definition of list. n. 1. A series of names, words, or other items written, printed, or imagined one after the other: a shopping list; a guest list; a list of things to d

Yes. These are called conditional expressions and these are used by the [[ compound command and the test and [ builtin commands ([ is simply a synonym for test).

Read section 6.4 Bash Conditional Expressions of the Bash Reference Manual, which contains a list of all these switches and their usage.

List of Wikipedias - Meta - Meta-Wiki, List definition is - a simple series of words or numerals (such as the names of persons or objects). How to use list in a sentence. Antigua and Barbuda. Antigua and Barbuda is a Commonwealth realm with 1 autonomous region, Barbuda. Member of the UNASUL. Barbados. Barbados is a Commonwealth realm. Belarus forms the Union State jointly with Russia . Member of the EU. Belize. Belize is a Commonwealth realm. Member of the UNASUL.

They are not switches for the if statement, but for the test command ([ is a synonym for the test builtin). See help test in bash for a complete list.

List, NIH is made up of 27 Institutes and Centers, each with a specific research agenda, often focusing on particular diseases or body systems. Placenames Tasmania Land Titles Office Office of the Valuer-General Land Tasmania Open Data Spatial Web Services Fruit Fly Information Spatial Discovery Aerial Photography Location Matters TASMAP Frequently Asked Questions Placenames Tasmania Land Titles Office Office of the Valuer-General Land Tasmania Open Data Spatial Web Services Fruit Fly

It's actually not if that's providing those — it's [, better known by the name of test. help test should give you a list of all options it can take. You could also look at the standard, if you care.

List of NIH Institutes, Centers, and Offices, Based on a recommendation by DHS and its intergovernmental partners, President Trump signed a proclamation on May 24 and amended on  Australian Birds: Photos and facts about birds of Australia including habitat, conservation, distribution maps

The single square brackets ([ ... ]) is an synonym of the test command. If you look at the manpage for test, you will see almost all (BASH might have a few extra not mentioned here) of the various if switches as you called them. All in one easy to find place.

If you use double square brackets ([[ ... ]]), you are using an extended BASH set of tests. These mainly have to do with regular expression matching, and glob matching (and extended glob matching if you have that set too). For that, you'll have to read that BASH manpage.

You called them if switches, but that's not really correct. These are tests and really have nothing to do with the if command.

The if command merely executes the command you give it, and then if that command returns an exit code of 0, will run the if portion of the if statement. Otherwise, it will run the else portion (if that's present).

Let's look at this:

$ rm foo.test.txt   # Hope this wasn't an important file
$ if ls foo.test.txt
> then
> echo "This file exists"
> else
> echo "I can't find it anywhere.."
> fi
ls: foo.test.txt: No such file or directory
I can't find it anywhere..

The if statement runs the ls foo.test.txt command and the ls command returns a non-zero because the file does not exist. This causes the if statement to execute the else clause.

Let's try that again...

$ touch foo.test.txt   # Now this file exists.
$ if ls foo.test.txt   # Same "if/else" statement as above
> then
> echo "This file exists"
> else
> echo "I can't find it anywhere.."
> fi
foo.test.txt
This file exists

Here, the ls command returned a 0 exit status (since the file exists and the file exists and can be stat'ed by the ls command.

Normally, you shouldn't use the ls command to test for a file. I merely used it here to show that the if statement executes the command, then executed the if or else clause depending upon the exit status of that command. If you want to test whether or not a file exists, you should use the test -e command instead of ls command:

if test -e foo.test.txt  # Same as above, but using "test" instead of "ls"
then
    echo "This file exists"
else
    echo "I can't find it anywhere.."
fi

If the file exists, test -e will return an exit status of 0. Otherwise, it will return a non-zero exit status.

If you do this:

$ ls -i /bin/test /bin/[
10958 /bin/[    10958 /bin/test

That 10958 is the inode. Files with the same inode are two different names for the same file. Thus [ and test command are soft linked1. This means you can use [ instead of test:

if [ -e foo.test.txt ]
then
    echo "This file exists"
else
    echo "I can't find it anywhere.."
fi

Looks familiar?


1. In BASH, the test and [ are builtin, so when you run these commands in BASH, it isn't running /bin/test or /bin/[. However, they're still linked to each other.

Department of Homeland Security Adds Brazil to List of Countries for , MINNEAPOLIS (WCCO) – On Wednesday, Gov. Tim Walz gave Minnesota restaurants the green light to open their patios starting on June 1,  Here are the prime numbers in the range 0 to 10,000. For more see Prime Number Lists.

A List Of Restaurants Reopening For Outdoor Dining – WCCO, This page lists current Emergency Use Authorizations that make available diagnostic and therapeutic medical devices to diagnose and respond to public health  Formed in 1990, List A is widely recognised as Australia’s leading list of commercial barristers with a national and international reputation for professional excellence and superior quality in the provision of legal services. Its senior practitioners are the leaders of the Victorian Bar and its members represent the Federal and State

Emergency Use Authorizations, Pandemic bankruptcies: A running list of retailers that have filed for Chapter 11. Tuesday Morning became the fifth major retailer file for  *The RSMS ROL list is a separate list of occupations that applies to the RSMS visa only. To respond to changes in the Australian labour market and regional variations across Australia, the list is reviewed regularly by the Department of Jobs and Small Business .

Retail bankruptcies during the coronavirus pandemic: A running list , Workers at New York State Veterans Home in St. Albans, Queens, demand justice for fallen veterans with an act of defiance, honor and  The Forbes World’s Billionaires list is a snapshot of wealth using stock prices and exchange rates from March 18, 2020. Some people become richer or poorer within days of publication.

Comments
  • gnu.org/software/bash/manual/bashref.html
  • [ is a short name for the test command. Try man test.
  • @Barmar you mean help test. man test is the documentation for /bin/test, and it supports different options from the test builtin
  • ffs just run man [!
  • -z is is an option to [ or test; it has nothing (directly) to do with if.
  • Online manual: Bash Conditional Expressions
  • Single page: 6.4 Bash Conditional Expressions
  • -1: test is both a command /bin/test and a bash builtin. man test gives you the doc for the command, but [ is a synonym for the builtin. As an example of divergent behavior, on OSX the bash builtin supports the -N test but the /bin/test does not
  • [ is not an alias of test. synonym is the word the manpage uses. Alias has a specific meaning (in the bash manpage, read the section ALIASES)
  • Okay. I'll change that. I was simply looking for a word that would explain how the two are linked.