Sponsored Content
Full Discussion: Condition in bash script
Top Forums UNIX for Beginners Questions & Answers Condition in bash script Post 303038798 by eckertd on Friday 13th of September 2019 11:38:18 AM
Old 09-13-2019
If you're looking to see if the specified file exists

Code:
if [ -f <filename> ]; then
  cp ....
else
  cp ...
fi

'-f' test if the file exists, and is a regular file (not a directory, etc)

See 'man test' for more conditions you can test for. They come in handy!
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Bash: if condition as variable

How can I use a variable that has the conditions for the if statement stored in it? my test script condition=" || || " if "$condition" then echo "true" else echo "false" fi output $ ./test2.sh ./test2.sh: line 3: || || : command not found false (2 Replies)
Discussion started by: curlee2002
2 Replies

2. Shell Programming and Scripting

Multiple condition checking in bash

Hi All, I am trying to check if two variables have value assigned to it. i am doing it like if ] then echo "Please specify either single hostname or host file for the report" usage exit fi But its not working for it.Even i specify values for both variables it dont go... (6 Replies)
Discussion started by: kailash19
6 Replies

3. Programming

if condition in bash

Hi, I have meaning to include an if condition statement in my code to check the directory for existing output files and if its existing i want the program to delete it before doing the succeeding command. i just dont know the correct syntax for it. thanks much guys, this forum has indeed been very... (4 Replies)
Discussion started by: ida1215
4 Replies

4. Red Hat

how to use if condition with sed command in BASH

Urgent help with bash scripting 1- i am using grep to find a string called: tinker panic 0 in a file /etc/ntp.conf if the string is not there, i want to add the strings in /etc/ntp.conf file in the first line of the file. if not do nothing or exit. 2- also i want to add # in front of the... (2 Replies)
Discussion started by: lamoul
2 Replies

5. UNIX for Dummies Questions & Answers

Bash condition test at the end of string

I want to check (using bash condition test function) if string contains three spaces, ignoring last three spaces at the end of string. string_to_report='foo bar foo bar ' string_to_ignore='foo bar ' (8 Replies)
Discussion started by: useretail
8 Replies

6. Shell Programming and Scripting

Add another condition to bash for when not met

In the below I can not seem to add a line that will add Not low if the statement in bold is not true or meet. I guess when the first if statement is true/meet then print low, otherwise print Not low in $(NF + 1). I am not sure how to correctly add this. Thank you :). if(low <= $2 && $2 <=... (5 Replies)
Discussion started by: cmccabe
5 Replies

7. Shell Programming and Scripting

Bash script if condition not executing

issue is with .txt files (7 Replies)
Discussion started by: anil529
7 Replies

8. Shell Programming and Scripting

Need Multiple checks inside if condition in a bash shell script

Hi, I need to perform the untar and rm operation if the file found is a .tar and does not have test.tar or hello.tar as the file names. Below is the loop to check the same. for tf in *.tar do if ] then found=1 ... (1 Reply)
Discussion started by: mohtashims
1 Replies

9. Shell Programming and Scripting

Creating a condition on a bash script

I wrote a code to find codons in a DNA string. The only problem I have is how do I make the code only work for a file with DNA. This means the file only has the characters a,c,g,t and no white space characters. (3 Replies)
Discussion started by: germany1517
3 Replies

10. UNIX for Beginners Questions & Answers

Awk/bash one liner replacement for a if condition

Hi. I wrote this small bash script, i want to compare second column from file1 with file2 if a pattern matches. Files are small and I am sure that pattern occurs only once. I think this can be rewritten into a awk one liner. Appreciate if someone could give me idea. Whole NR FNR confuse me :o ... (6 Replies)
Discussion started by: ctrld
6 Replies
TEST(1) 						    BSD General Commands Manual 						   TEST(1)

NAME
test, [ -- condition evaluation utility SYNOPSIS
test expression [ expression ] DESCRIPTION
The test utility evaluates expression and, if it evaluates to true, returns a zero (true) exit status; otherwise it returns 1 (false). If expression is not given, test also returns 1 (false). All operators and flags are separate arguments to the test utility. The following primaries are used to construct expression: -b file True if file exists and is a block special file. -c file True if file exists and is a character special file. -d file True if file exists and is a directory. -e file True if file exists (regardless of type). -f file True if file exists and is a regular file. -g file True if file exists and its set group ID flag is set. -h file True if file exists and is a symbolic link. -k file True if file exists and its sticky bit is set. -n string True if the length of string is nonzero. -p file True if file exists and is a named pipe (FIFO). -r file True if file exists and is readable. -s file True if file exists and has a size greater than zero. -t file_descriptor True if the file whose file descriptor number is file_descriptor is open and is associated with a terminal. -u file True if file exists and its set user ID flag is set. -w file True if file exists and is writable. True indicates only that the write flag is on. The file is not writable on a read-only file system even if this test indicates true. -x file True if file exists and is executable. True indicates only that the execute flag is on. If file is a directory, true indi- cates that file can be searched. -z string True if the length of string is zero. -L file True if file exists and is a symbolic link. This operator is retained for compatibility with previous versions of this pro- gram. Do not rely on its existence; use -h instead. -O file True if file exists and its owner matches the effective user id of this process. -G file True if file exists and its group matches the effective group id of this process. -S file True if file exists and is a socket. file1 -nt file2 True if file1 exists and is newer than file2. file1 -ot file2 True if file1 exists and is older than file2. file1 -ef file2 True if file1 and file2 exist and refer to the same file. string True if string is not the null string. s1 = s2 True if the strings s1 and s2 are identical. s1 != s2 True if the strings s1 and s2 are not identical. s1 < s2 True if string s1 comes before s2 based on the ASCII value of their characters. s1 > s2 True if string s1 comes after s2 based on the ASCII value of their characters. n1 -eq n2 True if the integers n1 and n2 are algebraically equal. n1 -ne n2 True if the integers n1 and n2 are not algebraically equal. n1 -gt n2 True if the integer n1 is algebraically greater than the integer n2. n1 -ge n2 True if the integer n1 is algebraically greater than or equal to the integer n2. n1 -lt n2 True if the integer n1 is algebraically less than the integer n2. n1 -le n2 True if the integer n1 is algebraically less than or equal to the integer n2. These primaries can be combined with the following operators: ! expression True if expression is false. expression1 -a expression2 True if both expression1 and expression2 are true. expression1 -o expression2 True if either expression1 or expression2 are true. ( expression ) True if expression is true. The -a operator has higher precedence than the -o operator. Note that all file tests with the exception of -h and -L follow symbolic links and thus evaluate the test for the file pointed at. GRAMMAR AMBIGUITY
The test grammar is inherently ambiguous. In order to assure a degree of consistency, the cases described in IEEE Std 1003.2 (``POSIX.2'') section 4.62.4, are evaluated consistently according to the rules specified in the standards document. All other cases are subject to the ambiguity in the command semantics. EXIT STATUS
The test utility exits with one of the following values: 0 expression evaluated to true. 1 expression evaluated to false or was missing. >1 An error occurred. STANDARDS
The test utility implements a superset of the IEEE Std 1003.2 (``POSIX.2'') specification. BSD
November 10, 2009 BSD
All times are GMT -4. The time now is 07:38 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy