Linked Questions

166
votes
1answer
482k views

How to clean log file? [duplicate]

Is there a better way to clean the log file? I usually delete the old logfile and create a new logfile and I am looking for a shorter type/bash/command program. How can I use an alias?
147
votes
1answer
18k views

Bash: What does “>|” do?

I have just seen this written down; $ some-command >| /tmp/output.txt Vertical pipes are used in standard redirects "piping" the output of one command to another, is >| in fact completely ...
142
votes
3answers
62k views

What's the difference between semicolon and double ampersand && [duplicate]

What is the difference between echo "Hello " ; echo "world" and echo "Hello " && echo "world" Both seems to run the two commands after each other.
119
votes
4answers
72k views

Precedence of the shell logical operators &&, ||

I am trying to understand how the logical operator precedence works in bash. For example, I would have expected, that the following command does not echo anything. true || echo aaa && echo ...
107
votes
4answers
62k views

What is the difference between “&&” and “;” when chaining commands [duplicate]

What is the difference between the following methods of chaining commands? cmd1; cmd2 cmd1 && cmd2
87
votes
2answers
247k views

Bash - how to run a command after the previous finished? [duplicate]

Currently I have a script.sh file with the following content: #!/bin/bash wget -q http://exemple.com/page1.php; wget -q http://exemple.com/page2.php; wget -q http://exemple.com/page3.php; I want to ...
75
votes
5answers
776k views

How to create a simple .txt (text) file using terminal? [closed]

I'm just trying to review basic terminal commands. Having said that, how do I create a text file using the terminal only?
67
votes
8answers
48k views

How can I make iconv replace the input file with the converted output?

I have a bash script which enumerates through every *.php file in a directory and applies iconv to it. This gets output in STDOUT. Since adding the -o parameter ( in my experience ) actually writes ...
59
votes
1answer
5k views

How is this command legal ? “> file1 < file2 cat”

Assuming file2 already exists, the command > file1 < file2 cat appears to be copying the content of file2 to file1. But I cannot understand this structure. I understand that "Nothing" is ...
53
votes
11answers
18k views

Is there a way to modify a file in-place?

I have a fairly large file (35Gb), and I would like to filter this file in situ (i.e. I don't have enough disk space for another file), specifically I want to grep and ignore some patterns — is there ...
41
votes
2answers
9k views

How does `cat <> file` work?

cat < file prints the contents of file to stdout. cat > file reads stdin until Ctrl+D is detected and the input text is written to file. cat <> file, at least in my version of Bash, ...
34
votes
2answers
19k views

Difference between executing multiple commands with && and ; [duplicate]

What's the difference between executing multiple commands with && and ;? Examples: echo "Hi\!" && echo "How are you?" and echo "Hi\!"; echo "How are you?"
29
votes
5answers
81k views

How to put a newline special character into a file using the echo command and redirection operator?

I would like to create a file by using the echo command and the redirection operator, the file should be made of a few lines. I tried to include a newline by "\n" inside the string: echo "first ...
26
votes
3answers
68k views

Can sed save its output to a file?

> can do it. echo "text" > file tee can do it. echo "test" | tee file Can sed do it without using either of the above? Is it possible to save the output of a sed command to a file without ...
26
votes
1answer
5k views

Where are bash line continuations after && and || documented?

I have seen this construct in scripts a lot and used it myself, but it bothers me that I can't seem to find it in the documentation. Example: [ -f file1 ] && [ -f file2 ] && echo "...

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