CODEWITHSUNDEEP
linuxbasharguments
Sky Scraper
Sky Scraper

Reputation: 301

How do I call the string content of a variable containing a filepath instead of the file at the end of the filepath? Bash/Linux

I want to give a script a file path, take the file name, assign the file name to a variable, then perform an action to the file at the file path.

Unfortunately, I do not know how to access the string content of the variable, instead of the file being held at the file path.

TestingScript.sh:

#!/bin/bash

egrep -o "[^/]+$" ${1} #get name of the file from the end of the filepath
wc -l $1 #count the number of lines in the file

Testing.txt

This
/is
the
text

Running it:

./TestingScript.sh "/User/Me/Directory/Testing.txt"

Instead of this returning:

Testing.txt
4 /User/Me/Directory/Testing.txt

This is the output:

/is
4 /User/Me/Directory/Testing.txt

Upvotes: 0

Views: 104

Answers (1)

Jonathan Leffler
Jonathan Leffler

Reputation: 754860

Converting comments into an answer.

Running echo "$1" | grep -E -o '^/.+' would run grep -E (aka egrep) on the name, but the regex doesn't match the last component of the name (you'd need '[^/]+$' for that, and the name couldn't end with a /). But the command you want is basename $1 (not least because basename /x/y/z/ reports z and even the revised grep regex fails on that). Incidentally, the -o option to grep (egrep) is a GNU extension.

Why does this matter "The -o option to grep (egrep) is a GNU extension"?

Not all copies of grep on the machines I use are GNU grep — all the world is not a Linux box. And you would either get an error message or different behaviour if the version of grep on the non-Linux box either does not support the -o option at all or does not use the option with the same meaning as GNU grep does. If you only work on Linux boxes, you don't have to worry about it; that's why it was an incidental comment.

I did not have an issue with '[^/]+$' — why do you say it fails?

Because echo /x/y/z/ | grep -o -E '[^/]+$' gives no output. If there is no trailing slash (which is used to force the name to be a directory), then there's no problem. It's a case of extremism — how can your script be broken by extreme inputs. If /x/y/z/ was a directory (or didn't exist), the wc command would fail too.

Upvotes: 1

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